Validation is in fact, the process of checking documents against this formal standard.Converting your HTML web pages to XHTML takes time. Validating your code is simply comparing it to W3C standards.Much as different languages have different rules of grammar, the code you use can have different rules depending on the doctype you use.If the validation fails, the response is then sent back to the client, page that contains the web form is refreshed and a feedback is shown.This method is secure because it will work even if Java Script is turned off in the browser and it can’t be easily bypassed by malicious users. Ajax calls to the server can validate as you type and provide immediate feedback.This will definitely help your website in the future.
So if you forget to close a tag, Firefox might ignore this but Safari doesn’t and you end up with a broken layout.
One of the discussions that arises from time to time in web development circles is that of validating your code. It’s no different than comparing a sentence you write to the rules of grammar for the language you wrote it in.
Some will insist your pages need to validate 100% and others will tell you it’s not even worth checking as long as your pages work. In fact the grammar analogy is a good one to keep in mind when you think of validating your code.
XHTML is the newest standard for this hybrid markup language designed for web documents.
It is a combination of classic HTML and advanced XML.