A HTML validator checks whether your site has a valid HTML or not. After your website has been created, it is important to upload it to a HTML validator. It is run by the standard body of the Web. It not only checks the website but it also gives you an idea how to fix any problem.

This step is essential in the field of website development because:

Correct Code
Testing your codes for validation ensures that your code is correct and will work properly on every web browser. If it is not checked, it might often lead to a situation where it might not work on a number of browsers. Even if the code is marginally incorrect it would display unexpected errors on the page. If validators are not used, one will have to develop completely different website for different browsers.

Valid Pages and preferred by Search Engines
A search would understand a valid page much easily than an invalid one. So, a valid page would naturally get a higher rank in the search. However, if your site has not been validated, the search engine will not be able to understand your keywords and might list illogical parts of your code under your site's name. This would drive the traffic away from your site.

Mobile Devices
An increasing number of people now make the use of PDAs and Mobile phones for web access. These devices suffer from even more problems due to the invalid codes. Due to their limited processing capacity, they are unable to solve the mystery behind the invalid codes. It would just remove all of the  formatting from the page. So, a valid HTML is a must.

Disabled People
For devices such as screen readers, valid HTML codes are a must. While working with programs meant for disabled, it is even more important that your HTML must be completely valid.

Future Proofing
It is important to declare which version of HTML you intend to validate the codes for. For instance, a valid XHTML 1.1 page will remain so even when others have moved to XHTML 5. This future-proofs your code. Validation ensures that your site will remain viewable for a long time.

Error Finding
Validation helps to find out any errors in your code and helps to correct it. Earlier, it was necessary for people to test their site after they make any changes. These programs point out the exact place where the code is invalid.

A List of validators
HTML validators are easily available Online. Few of the most widely used validators are:

* The W3C validator
* The WDG validator
* Doctor HTML
* WebTechs validator
* CSE validator