Validating Your HTML: Tools and Techniques

When you’re learning HTML, it’s easy to make tiny mistakes that break your page or make it look strange. Missing tags, wrong spellings, or a forgotten quote can cause big headaches.

That’s where HTML validation comes in. In this article, you’ll learn what validation is, why it matters, and how to use simple tools to check and fix your HTML, step by step.

What Does “Validating HTML” Mean?

HTML validation is the process of checking your web page’s HTML code against the official rules (called “standards”).

Think of it like a spell checker for your website. Instead of spelling errors, it looks for code errors.

Validation helps you:

Find and fix mistakes quickly
Make your website work better across different browsers
Improve your chances of good search engine visibility
Build good habits as you learn to code

You can write a page that seems to work, but still has hidden errors. A validator helps you spot those.

Step 1: Start With a Simple HTML Page

Let’s begin with a very simple HTML file that has a few common mistakes.

Create a new file on your computer and name it example.html, then paste this code inside:

<!DOCTYPE html>
<html>
<head>
  <title>My First Page</title>
</head>
<body>
  <h1>Welcome to my page<h1>

  <p>This is a paragraph about me.

  <img src="photo.jpg alt="My photo">

  <a href="https://example.com">Visit example.com
</body>
</html>

This code will probably still show something in your browser, but it has several errors:

The <h1> tag is not properly closed
The <p> tag is not properly closed
The <img> tag has a broken attribute
The <a> link tag is missing its closing </a>

You might not notice all these just by looking. Let’s use tools to help.

Step 2: Use the W3C HTML Validator (Online Tool)

The W3C Markup Validation Service is a free, official tool used by developers worldwide.

How to use it

Open this site in your browser:
https://validator.w3.org/
Click the “Validate by Direct Input” tab.
Copy all the code from your example.html file.
Paste it into the big text box.
Click “Check”.

The validator will scan your code and show a list of errors and warnings.

Each error usually includes:

The line number (where the problem is)
A short message describing the issue
Sometimes a tip for how to fix it

Don’t worry if the messages look technical at first. You’ll learn by fixing one issue at a time.

Step 3: Fixing Common HTML Errors

Let’s fix our example.html based on the errors you’ll see.

1. Close your heading tag

The validator should complain about <h1> not being closed properly.

Wrong:

<h1>Welcome to my page<h1>

Correct:

<h1>Welcome to my page</h1>

The closing tag uses a slash: </h1>.

2. Close your paragraph tag

HTML paragraphs should be wrapped in <p> and </p>.

Wrong:

<p>This is a paragraph about me.

Correct:

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

Some browsers will guess what you meant, but a validator will still flag it.

3. Fix image attributes

The <img> tag needs correctly written attributes. Each attribute must be inside the tag, with quotes correctly closed.

Wrong:

<img src="photo.jpg alt="My photo">

The quotes are broken, so the browser gets confused.

Correct:

<img src="photo.jpg" alt="My photo">

src tells the browser which image file to load.
alt is a text description for screen readers and when the image can’t load.

4. Close your link tag

Links use <a> (anchor) tags and should always be closed.

Wrong:

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

Correct:

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

Now the browser knows exactly where the link text begins and ends.

Step 4: Check Your Fixed HTML

Update your example.html file so it now looks like this:

<!DOCTYPE html>
<html>
<head>
  <title>My First Page</title>
</head>
<body>
  <h1>Welcome to my page</h1>

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

  <img src="photo.jpg" alt="My photo">

  <a href="https://example.com">Visit example.com</a>
</body>
</html>

Now go back to the W3C validator:

Paste this updated code again.
Click “Check”.

You should now see a message saying something like “Document checking completed. No errors or warnings to show.”

That means your HTML is valid according to the rules.

Try it yourself

Change the text inside <h1> or <p> to something else, save the file, and validate again. As long as you only change the text between the tags, your HTML should stay valid.

This is a safe way to experiment and build confidence.

Step 5: Using Built-In Editor Tools (VS Code Example)

If you use a code editor like Visual Studio Code (VS Code), it can help catch some issues as you type.

Setup (optional but helpful)

Download and install VS Code (search for “Visual Studio Code download”).
Open VS Code and create a new file called page.html.
Paste this slightly more complex example:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Profile Page</title>
</head>
<body>
  <!-- Main heading -->
  <h1>About Me</h1>

  <!-- Intro paragraph -->
  <p>Hello, my name is Taylor and I love learning HTML!</p>

  <!-- A list of hobbies -->
  <ul>
    <li>Reading</li>
    <li>Coding</li>
    <li>Traveling</li>
  </ul>
</body>
</html>

Many editors will highlight problems like missing closing tags automatically. If you remove </ul> or </li>, you may see warnings.

You can still paste this code into the W3C validator to double-check it.

Step 6: Add One Error on Purpose

A powerful way to learn is to break things on purpose and then fix them.

Try removing one closing tag from the previous example. For instance, delete the closing </p> tag:

<p>Hello, my name is Taylor and I love learning HTML!

Now validate your page again using the W3C tool.

Notice how the validator reports the error.
Look at the line number and message.
Fix the code and validate again.

Over time, you’ll start to predict what the validator will say.

Other Helpful Validation Tips

1. Validate often

Don’t wait until your page is huge. Validate every time you:

Add a new section
Create a new page
Make big changes

Fixing small errors early is much easier than hunting down many problems at once.

2. Read error messages slowly

Error messages can seem scary, but break them down:

Look at the line number first.
Read the message word by word.
Compare your code to a working example.

If you still feel stuck, copy the error message into a search engine. Many people have asked the same questions before.

3. Don’t chase perfection at first

It’s okay if you don’t understand every warning right away. Focus on:

Fixing errors (red messages) first
Then dealing with warnings when you feel ready

The goal is to learn and improve, not to be perfect on day one.

Try It Yourself: Build and Validate a Mini Page

Create a new file called bio.html and try writing this from scratch (without copying):

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>My Bio</title>
</head>
<body>
  <h1>Hi, I'm [Your Name]</h1>

  <p>I am learning HTML and practicing validation.</p>

  <img src="my-photo.jpg" alt="A photo of me">

  <a href="https://www.google.com">My favorite website</a>
</body>
</html>

Steps:

Replace [Your Name] with your real name.
Save the file.
Paste the code into the W3C validator.
Fix any errors it finds.

Celebrate when you see no errors. That’s a real achievement.

Quick Recap and What’s Next

Here’s what you learned:

Validation checks your HTML against official rules, like a spell checker for code.
The W3C Validator is a free online tool that shows you exactly where your HTML has mistakes.
Small issues like missing closing tags, broken attributes, and unclosed links are very common—and easy to fix once you know how.
Validating often helps you build good habits and makes your pages more reliable.

As your next step, try adding more elements to your pages—like lists, images, and links—and validate every time you add something new. Over time, you’ll make fewer mistakes, and validation will become a quick final check instead of a long debugging session.

You’re already doing real web development work by writing HTML and fixing validation errors. Keep going—every small fix is a step forward in your coding journey.

Mudzinga