Understanding HTML – How it Works and Basic Applications

What is HTML?

HTML (short for HyperText Markup Language) is a markup language used to build and structure content on web pages. HTML plays a fundamental role in helping web browsers understand and display information visually to users. The unique aspect of HTML is its ability to format content through tags and attributes, which create elements such as paragraphs, images, links, tables, and many other components on a webpage. However, HTML is not a programming language, but rather a language used to define the structure and layout of web documents.

With the popularity of modern programming tools and browsers, understanding HTML not only helps you build basic web pages but also serves as a starting point for exploring more advanced technologies in web development.

History and Development of HTML

HTML was created in 1991 by computer scientist Tim Berners-Lee – the inventor of the World Wide Web. Initially, HTML consisted of 18 basic tags that allowed defining simple elements such as headings, paragraphs, and links. This version was primarily used to share documents among researchers.

Over time, HTML has been continuously improved to meet the rapidly evolving needs of web technology. Key versions include:

• HTML 2.0 (1995): The first standard version, adding tags like <table> and <form> to enhance display and interaction capabilities.
• HTML 3.2 (1997): Introduced support for CSS, helping to separate content from design.
• HTML 4.01 (1999): Enhanced customizability and multimedia support.
• HTML5 (2014): The latest version, offering robust integration with multimedia such as audio, video, and supporting advanced web applications.

With each development phase, HTML not only expanded in features but also improved compatibility across browsers. This has made HTML an essential language for building websites, from basic sites to complex web applications today.

Is HTML a Programming Language?

One of the most common questions is: "Is HTML a programming language?" The answer is no. HTML is not a programming language but a markup language. This means that HTML cannot perform calculations, conditions, or logical processing – core elements of a programming language.

Reasons HTML is Not a Programming Language:

• No conditional logic: HTML does not support conditional statements like if, else, or loops (for, while).
• No variables or functions: You cannot declare variables or write functions in HTML.
• Focuses on defining structure: HTML is solely concerned with organizing and displaying content through tags.

Although not a programming language, HTML still plays a core foundational role in web development. It provides the framework for other technologies like CSS and JavaScript to operate, creating complete web pages. This is why every web developer must master HTML before advancing further.

Role of HTML in Web Development

HTML serves as the core foundation in web development, where every element of a webpage begins with defining and structuring content using this language. Without HTML, websites would not be able to display content or interact with users effectively.

Key Roles of HTML:

1. Building Website Structure: HTML helps define the main components of a webpage, such as headings, paragraphs, images, links, and tables. For example:

   <header>
     <h1>This is the main title of the page</h1>
   </header>
   

2. Integrating Multimedia: HTML supports embedding multimedia content such as videos, audio, and images, making websites more dynamic. With HTML5 improvements, embedding these files has become easier and more flexible. Example:

   <video controls>
     <source src="video.mp4" type="video/mp4" />
     Your browser does not support the video tag.
   </video>
   

3. Interaction with CSS and JavaScript: HTML provides the framework for CSS to style the interface and JavaScript to add interactivity. This combination results in modern websites that optimize user experience.

4. Supporting SEO (Search Engine Optimization): HTML allows the use of tags like <title>, <meta>, and <h1> to help search engines understand the content of the webpage. This is crucial for improving search rankings.

In general, HTML is not only the "raw material" in web development but also the tool that connects other technologies, ensuring that a website operates effectively both technically and in terms of user experience.

Advantages and Disadvantages of HTML

Like any other technology, HTML has its strengths and limitations. Understanding its pros and cons will help you use HTML more effectively in web development.

Advantages of HTML:

1. Easy to Learn and Use:

   • Simple and easy-to-understand syntax, suitable for beginners.
   • No need for complicated software installation – just a text editor and a browser.

2. Widely Supported:

   • HTML is the foundation of most websites, supported by all modern browsers such as Chrome, Firefox, and Safari.
   • It has a large community with many detailed resources and tutorials.

3. Platform Independent:

   • HTML works on all operating systems, including Windows, macOS, Linux, and mobile devices.

4. Integration Capabilities:

   • Works well with technologies like CSS and JavaScript to create attractive and interactive interfaces.
   • Supports embedding multimedia (images, audio, video) and integrating APIs in HTML5.

Disadvantages of HTML:

1. Static Nature:

   • HTML can only create static websites and cannot handle logic or dynamic interactions without the support of JavaScript or other languages.

2. Limitations for Large Projects:

   • For complex websites or large projects, pure HTML can become difficult to manage and may require additional support from frameworks or CMS (Content Management Systems).

3. Dependency on CSS and JavaScript:

   • HTML only focuses on structure, while the layout and interactive features entirely rely on CSS and JavaScript.

4. Lack of Security:

   • Pure HTML does not have built-in security mechanisms, making it vulnerable if not used correctly when combined with server-side technologies.

Overall, HTML is a powerful tool for starting to learn web development, but to build dynamic and professional web applications, you need to combine it with other supporting technologies.

Key HTML Terms You Need to Know

When starting to learn HTML, you'll come across some basic terms that you need to understand to work efficiently and accurately. Below are some of the most common terms in HTML:

Tag:

• Tags are the fundamental elements in HTML, used to define items on a webpage. Each tag usually has an opening and closing tag. Example:

  <p>This is a paragraph of text</p>
  

Attribute:

• Attributes are used to provide additional information about a tag. They are placed inside the opening tag and follow the structure: attribute="value". Example:

  <a href="https://www.example.com">Link</a>
  

  Here, href is an attribute of the <a> tag, specifying the URL the link will point to.

Element:

• An element in HTML is a tag and all of its content, including the opening tag, content, and closing tag. Example:

  <h1>Main Heading</h1>
  

  In this case, the element is the <h1> tag and the content "Main Heading".

DOM (Document Object Model):

• The DOM is an object model that helps the browser understand and manipulate HTML elements as objects within a tree structure. The DOM allows JavaScript to modify the content and structure of a webpage after it has loaded.

Source Code:

• Source code refers to the actual HTML code written by the developer, which the browser will read to render the webpage. You can view the source code of any webpage by right-clicking and selecting "View Page Source."

HTML Entity:

• An HTML Entity is a special character represented by numeric codes or symbols instead of the character itself. For example, to display a double quote (") in HTML, you would use ".

Doctype:

• Doctype is used to declare the document type of the webpage and specify the HTML version the browser will use to interpret the source code. Example:

  <!DOCTYPE html>
  

Understanding these terms will help you approach and work with HTML more easily, while also enhancing your web development skills effectively.

Common HTML Tags You Will Use

When working with HTML, there are a few basic tags that you will frequently use to build the structure of a webpage. Below is a list of popular tags and their functions:

<html>:

• This tag defines an HTML document. All content of the webpage is placed within the <html> tag.

  <html>
    <head>
      <title>My Website</title>
    </head>
    <body>
      <p>This is the content of the webpage.</p>
    </body>
  </html>
  

<head> and <body>:

• The <head> tag contains information like the page title, links to CSS, and other data that isn't directly displayed on the page.
• The <body> tag contains all the content that the user will see on the web page.

  <head>
    <meta charset="UTF-8" />
    <title>Page Title</title>
  </head>
  <body>
    <h1>Welcome to my website</h1>
    <p>This is a paragraph of text.</p>
  </body>
  

<h1> to <h6>:

• These tags are used to create headings from largest to smallest. <h1> is the largest heading, while <h6> is the smallest.

  <h1>Main Heading</h1>
  <h2>Sub Heading</h2>
  

<p>:

• The <p> tag is used to define a paragraph of text. This is the most basic tag and is used very frequently in HTML.

  <p>This is a paragraph of text on the web page.</p>
  

<a>:

• The <a> tag is used to create a hyperlink. You can link to another webpage or a different section of the current page.

  <a href="https://www.example.com">Go to Example Page</a>
  

<img>:

• The <img> tag is used to embed an image on the webpage. You need to use the src attribute to specify the path to the image.

  <img src="image.jpg" alt="Image description" />
  

<ul>, <ol>, and <li>:

• These tags are used to create unordered lists (<ul>) or ordered lists (<ol>), with each list item defined by the <li> tag.

  <ul>
    <li>Item 1</li>
    <li>Item 2</li>
  </ul>
  

<table>, <tr>, <td>:

• The <table> tag creates a table, the <tr> tag creates a row, and the <td> tag is used to create a cell in the table.

  <table>
    <tr>
      <td>Cell 1</td>
      <td>Cell 2</td>
    </tr>
    <tr>
      <td>Cell 3</td>
      <td>Cell 4</td>
    </tr>
  </table>
  

<form>, <input>, <button>:

• The <form> tag is used to create a form for data entry, the <input> tag creates input fields, and the <button> tag is used to create a button.

  <form>
    <input type="text" placeholder="Enter name" />
    <button type="submit">Submit</button>
  </form>
  

Mastering these basic HTML tags will help you easily build and structure web pages while improving your ability to interact with other web technologies like CSS and JavaScript.

Basic Layout of HTML

When you start building a webpage, understanding and applying the basic layout of HTML is crucial to ensure proper organization and easy expansion later. The basic layout of an HTML document includes essential sections like: the DOCTYPE declaration, the <html>, <head>, and <body> tags. These structural components help browsers interpret and display the content of the web page.

Basic Structure of an HTML Document:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>My Website</title>
  </head>
  <body>
    <header>
      <h1>Welcome to my website</h1>
    </header>

    <nav>
      <ul>
        <li><a href="#home">Home</a></li>
        <li><a href="#about">About</a></li>
        <li><a href="#contact">Contact</a></li>
      </ul>
    </nav>

    <main>
      <section>
        <h2>About</h2>
        <p>This is an introduction about me.</p>
      </section>

      <section>
        <h2>My Projects</h2>
        <p>Here are the projects I've worked on.</p>
      </section>
    </main>

    <footer>
      <p>&copy; 2025 My Website. All rights reserved.</p>
    </footer>
  </body>
</html>

How to Write Valid HTML Code

To ensure your website works effectively and is easy to maintain, it is important to write valid HTML code. This not only makes your site easier to read and troubleshoot but also improves performance and compatibility with search engines and various browsers.

Here are some basic principles for writing valid HTML code:

Use a Proper Structure:

• Always start with the <!DOCTYPE html> declaration to indicate that the document uses HTML5.
• Make sure the <html> tag surrounds the entire document.
• Place tags like <head> and <body> in the correct locations, with <head> containing metadata and <body> containing the page content.

Example of Proper Structure:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>My Website</title>
  </head>
  <body>
    <!-- Page content goes here -->
  </body>
</html>

Use Clear and Consistent Naming for Tags and Attributes:

• Use standard HTML tag names and avoid abbreviations. For example, instead of using <img src="logo.png">, use valid and understandable tags.
• Use clear and understandable names for attributes. For instance, use alt instead of description when describing an image.

Ensure Tags are Properly Opened and Closed:

• Every opening HTML tag must have a corresponding closing tag. For example:

  <p>This is a paragraph.</p>
  

Indent and Align the Source Code:

• Use indentation to make the code more readable and easier to debug when necessary. Ensure that the source code is aligned properly, with nested elements indented correctly.

Example of Proper Indentation:

<html>
  <head>
    <meta charset="UTF-8" />
    <title>Page Title</title>
  </head>
  <body>
    <h1>Welcome to my website</h1>
    <p>This is the content of the webpage.</p>
  </body>
</html>

Use Semantic Tags When Possible:

• Semantic tags (tags that clearly define content) help improve code readability, making it easier for search engines and browsers to understand the page structure. For example, instead of using <div> for headings, use the <header> or <h1> tags.

Example of a semantic tag:

<header>
  <h1>Welcome to My Website</h1>
</header>

Create Maintainable Code:

• Write understandable and organized code so that others can easily maintain it in the future. Use clear names for tags, variables, and attributes to make it easier to modify the code later.

Check Code Compatibility:

• Ensure that your code works across different browsers and devices. Test your website on browsers such as Chrome, Firefox, Safari, and Internet Explorer.

By following these principles, you'll write clean, readable, and maintainable HTML code. This not only improves the performance of your website but also optimizes it for both users and search engines.

Difference Between HTML and HTML5

When it comes to HTML and HTML5, many people may confuse them since they are both versions of the markup language for the web. However, HTML5 is the latest version and has significant improvements over earlier versions of HTML. Below is the distinction between the two versions:

HTML (HyperText Markup Language):

• HTML is the markup language used to build the structure of web pages. Early versions of HTML (HTML 1.0, HTML 2.0, HTML 3.2) provided basic tags like <p>, <h1>, <a>, but they lacked advanced features to support modern web applications.

HTML5 (The Latest Version):

• HTML5 is recognized as the most modern and powerful version of HTML. It not only improves basic tags but also adds new features that support more complex web applications, making web development easier and more powerful.

• Some key features of HTML5 include:

  • Support for video and audio: HTML5 introduces the <video> and <audio> tags, allowing media files like videos and audio to be embedded directly into web pages without needing additional plugins like Flash.

    <video width="320" height="240" controls>
      <source src="movie.mp4" type="video/mp4" />
      Your browser does not support the video tag.
    </video>
    

  • New Semantic Tags: HTML5 introduces new semantic tags like <header>, <footer>, <article>, <section>, making document structure clearer and easier to understand. This helps search engines and screen readers better understand the content of a webpage.

    <header>
      <h1>Welcome to My Website</h1>
    </header>
    

  • Local Storage and Session Storage: HTML5 allows for data storage on the user's browser through localStorage and sessionStorage. This improves the user experience by storing data on their device without needing to send requests to the server.

    localStorage.setItem('username', 'JohnDoe');
    var username = localStorage.getItem('username');
    

  • APIs for Web Application Development: HTML5 provides many new APIs, such as the Geolocation API, Canvas API, Web Workers, and more, allowing developers to create dynamic and smooth web applications.

Differences Between HTML and HTML5:

Thus, HTML5 brings significant improvements in interactivity and multimedia support, allowing developers to build modern web applications that meet users' growing demands. On the other hand, earlier versions of HTML primarily focused on the basic structure of a web page.

The Interplay Between HTML, CSS, and JavaScript in Web Development

When building a website, HTML, CSS, and JavaScript are three essential components. Each has its own role and function, but they are closely interconnected to create a complete and smooth user experience.

HTML (HyperText Markup Language):

• As previously mentioned, HTML is responsible for providing the basic structure for a web page. It defines elements such as headings, paragraphs, images, links, and other basic components that users interact with.
• HTML provides the structure for a website, but it does not control how these elements are displayed or interact.

CSS (Cascading Style Sheets):

• CSS is the language used to format and style HTML elements. It helps define how these elements will be displayed on the page, including colors, fonts, spacing, layout, and animations.
• CSS works alongside HTML to enhance user interface, making the web page not only structured but also visually appealing and user-friendly.
• For example, you can use CSS to change the background color of a page, align text, or add hover effects to buttons.

Example of using CSS with HTML:

<style>
  body {
    background-color: lightblue;
  }
  h1 {
    color: red;
  }
</style>
<h1>Welcome to my website!</h1>

JavaScript:

• JavaScript is the programming language used to create dynamic features on a web page. With JavaScript, you can change the content of a page without reloading it, handle events like clicks, user input, and many other functions to enhance user experience.
• JavaScript is the key element that increases interactivity on the web, enabling the creation of online games, dynamic applications, or even single-page applications (SPAs).

Example of using JavaScript to change content when a button is clicked:

<button onclick="changeContent()">Click here</button>
<p id="text">Initial content.</p>

<script>
  function changeContent() {
    document.getElementById('text').innerHTML = 'Content has changed!';
  }
</script>

The combination of HTML, CSS, and JavaScript:

• HTML provides the structure, CSS styles that structure, and JavaScript makes the page dynamic and interactive. All three elements together form a complete web that users can easily use and interact with.
• You can think of this combination like a trio: HTML is the skeleton of the webpage, CSS is the skin that makes the webpage look good, and JavaScript is the muscle that brings actions and responses when users interact.

Understanding the relationship between HTML, CSS, and JavaScript not only helps you build effective websites but also expands your creative possibilities, allowing you to create unique and engaging web experiences.

Basic SEO with HTML

When building a website, SEO (Search Engine Optimization) is a crucial factor to ensure that your website can be easily found on search engines like Google. One of the key factors for optimizing SEO is proper use of HTML. Here are some basic techniques to improve the SEO of your site using HTML:

Using Title Tags:

• The title tag is one of the most important elements for SEO. It defines the name of the page and appears in the browser tab as well as in Google search results.
• To optimize SEO, the title tag should contain the main keyword related to the page's content and accurately describe the page's content.

Example:

<title>Learn Basic HTML - HTML Knowledge from A to Z</title>

For detailed reference on how to optimize title tags, visit https://riverlee.vn/en/blog/what-is-seo-title.

Using Meta Description Tags:

• Meta Description is a brief description of the page's content. Although Google doesn't use this tag directly for ranking, this description is displayed in search results and can influence whether users click on your link.
• Make sure that the meta description contains relevant keywords and provides a concise, attractive summary of the page's content.

Example:

<meta
  name="description"
  content="Learn basic HTML with detailed guides, from tags creation to SEO optimization for your website."
/>

Using Heading Tags (H1, H2, H3, ...):

• Heading tags help define the structure of the page content and help search engines understand the important parts of the article.
• H1 is the most important tag and should appear only once per page. H2 and H3 tags help create subheadings, making the page easier to read and understand.

Example:

<h1>Basic HTML Guide</h1>
<h2>Introduction to HTML</h2>
<h3>Basic HTML Tags</h3>

Using alt tags for images:

• Search engines cannot "read" images, so using the alt tag for every image helps describe the image content for search engines and users who need screen reader support.
• The alt tag also supports SEO by allowing the keywords in the image description to improve ranking.

Example:

<img src="html-guide.jpg" alt="Basic HTML guide for beginners" />

Internal Links:

• Internal links help users navigate through other pages on your website and help search engines better understand the structure of the website.
• When building internal links, make sure the links have relevant keywords and accurately describe the content of the linked page.

Example:

<a href="html-tag-guide.html">Learn about basic HTML tags</a>

Using SEO-friendly URLs:

• Make sure your URLs are short, easy to understand, and contain relevant keywords. This not only helps users easily recognize the content of the page but also helps search engines assess the page's content more accurately.

Example:

<a href="https://www.example.com/basic-html-guide">Basic HTML Guide</a>

By optimizing these elements in HTML, you can improve the ranking of your website on search engines, making it easier for users to find your site and enhancing the overall SEO effectiveness.

Popular HTML Programming Software

When starting to learn or develop websites with HTML, choosing the right programming software is crucial. These tools help you write code more easily, provide features that support web development, check for errors, and even manage web projects effectively. Below are some popular HTML programming software that are favored by many developers:

Visual Studio Code (VS Code)

• Visual Studio Code is one of the most popular programming tools today. It supports HTML, CSS, JavaScript, and many other programming languages very well. VS Code provides features like auto-completion, syntax highlighting, extensions (to extend functionality), and Git integration.
• Especially, VS Code supports many extensions that make HTML programming easier, such as live preview support, HTML syntax error checking, and many plugins to improve work efficiency.

Download Visual Studio Code at https://code.visualstudio.com.

Sublime Text

• Sublime Text is a lightweight and fast code editor. It has a simple, easy-to-use interface but still provides powerful features like syntax highlighting, auto-completion, and multi-caret editing to help developers work more efficiently.
• Sublime Text also supports many plugins that enhance its functionality, but it's worth noting that this software is not entirely free (although it offers a free trial).

Download Sublime Text at https://www.sublimetext.com.

Atom

• Atom is an open-source, free, and highly customizable code editor. Atom offers features like syntax highlighting, auto-completion, and high customizability through plugins.
• One of Atom's standout features is Live Preview, which lets you see changes to your webpage in real-time when editing HTML code without needing to reload the browser.

Download Atom at https://atom.io.

Notepad++

• Notepad++ is a free, lightweight, and easy-to-use tool for beginners learning HTML programming. It supports many programming languages and can be extended with plugins. While not as powerful as VS Code or Sublime Text, Notepad++ is a popular choice due to its simple interface and quick response time.
• Notepad++ has syntax highlighting and helps check HTML, CSS, and JavaScript syntax quickly.

Download Notepad++ at https://notepad-plus-plus.org.

Brackets

• Brackets is a free and open-source code editor designed specifically for web development. It offers features like Live Preview, allowing you to view HTML code changes directly in the browser without refreshing.
• One of Brackets' unique features is Quick Edit, which lets you edit CSS, HTML, and JavaScript code in the same window without switching between files.

Download Brackets at http://brackets.io.

XAMPP

• XAMPP is software that helps create a server environment on your personal computer, supporting web technologies like PHP, MySQL, and Apache. While XAMPP is not a code editor, it is very useful when you want to test dynamic web applications built with HTML and PHP. XAMPP allows you to easily set up and use a web server on your computer.

Download XAMPP at https://www.apachefriends.org.

Pinegrow

• Pinegrow is a powerful web development tool that lets you create and edit HTML pages directly using a drag-and-drop interface. It's useful for those who want to build web interfaces without writing code from scratch, although you can still edit HTML and CSS code within this software.

Download Pinegrow at https://pinegrow.com.

Free HTML Learning Resources

When starting to learn HTML, there are many free learning resources available online that you can take advantage of. These resources will help you master the basics, from writing HTML code to optimizing your website and developing more complex projects. Below are some quality free HTML learning resources you can explore:

MDN Web Docs (Mozilla Developer Network)

• MDN Web Docs by Mozilla is one of the most reliable and popular resources for learning HTML. It offers detailed articles on HTML, CSS, JavaScript, and many other web development topics. You can find guides from beginner to advanced levels, along with code examples and clear explanations.
• MDN Web Docs has a large community and the documentation is regularly updated.

Visit at https://developer.mozilla.org/en-US/docs/Web/HTML.

W3Schools

• W3Schools is one of the most famous websites for learning web programming. It offers free lessons on HTML, CSS, JavaScript, SQL, PHP, and many other technologies. The lessons on W3Schools are easy to understand, with real-world examples that help you learn quickly and effectively.
• W3Schools also offers a try-it-yourself tool that allows you to practice writing HTML code directly on the website without the need to install software.

Visit at https://www.w3schools.com.

freeCodeCamp

• freeCodeCamp is a very popular free coding platform. It offers online courses on HTML, CSS, JavaScript, and many other web technologies. freeCodeCamp not only provides theoretical lessons but also hands-on exercises that allow you to apply what you've learned to real-world projects.
• After completing the course, you can receive a free certificate to verify your programming skills.

Visit at https://www.freecodecamp.org.

Codecademy

• Codecademy is a well-known online learning platform. Codecademy offers free and paid courses on HTML, CSS, JavaScript, and many other programming languages. Codecademy courses are designed with short and interactive lessons that help you learn by practicing directly in the browser.
• Codecademy offers a free basic HTML course that is perfect for beginners.

Visit at https://www.codecademy.com.

Coursera

• Coursera is an online learning platform offering courses from renowned universities and organizations worldwide. Although many of the courses on Coursera are paid, you can still learn for free by choosing the "audit" mode (free trial). Coursera offers in-depth HTML, CSS, and web development courses taught by experts from prestigious universities.
• Coursera provides specialized courses with certificates upon completion, helping you enhance your skills and build your professional profile.

Visit at https://www.coursera.org.

HTML.com

• HTML.com is a simple and easy-to-understand HTML learning resource offering detailed lessons from basic to advanced levels. It's one of the best places to start learning HTML, with accessible explanations and real-life examples.

Visit at https://www.html.com.

YouTube

• YouTube has many free coding channels, including HTML tutorials. You can find video tutorials from beginner to advanced levels that suit any skill level. Some popular channels include:
  • The Net Ninja: Offers video tutorials on HTML and other web technologies.
  • Traversy Media: Specializes in web programming videos, including HTML, CSS, JavaScript.

Search "HTML tutorial" on YouTube to explore more.

Conclusion

In this article, we have explored and learned about HTML—one of the most fundamental and important aspects of web programming. From understanding what HTML is, its history, to the basic tags, the relationship between HTML, CSS, and JavaScript, as well as how to optimize your website with SEO. Additionally, mastering how to write clean HTML code and using the right programming software will improve your work efficiency and enhance user experience on websites.

Learning HTML is not a quick process, but with persistence and the variety of free learning resources available on the Internet, you can easily develop and improve your web programming skills. Don't hesitate to start from the basics and gradually advance your coding skills to create engaging and user-friendly websites.

Continue exploring the tools and resources we have shared in this article to support you on your web programming journey. Good luck, and don't forget to apply your knowledge in practice to enhance your skills!