Not all validators check for the same things in website. Some only check CSS, others text field, others input values and others for accessibility. If you are sincere in presenting standardized pages to the public, test them with several validators.
Validators detect problems in your web page and style sheet. It could be a tag that was opened and never closed. It could be a misspelled piece of code or forgotten element the tag or style requires working properly. You become a detective, hunting and solving the little problems occurring in your web page.
Validation errors aren't limited to your template files. They can also happen inside of a post. When you are writing a post and using HTML, WordPress might not recognize the HTML and convert it to a character entity, or you may have entered it wrong. If you have a page with a lot of HTML coding, validate it to make sure you have it all correct.
Validation doesn't just mean putting your pages through some web driven testers. It also means test-driving it with friends, relatives, co-workers, and strangers. Everyone has a different system and way of working, so ask for others to test-drive your styles or themes before you make them public. There are some validation checklist is used to validate WordPress Website. Let’s see that validation checklist points:
1. Validate HTML/ XHTML
2. Validate CSS file
3. Validate Comments/Feedback
4. Validate Input Field Value (like text field, text area etc )
5. Validate Links
6. Validate Install Theme or custom theme
7. Validate Plugin (custom plugin code)
8. Validate URL Structure of WordPress website
9. Validate Categories and blogs
10. Validate to check across different browser (include handheld computer, Mac, PC and cell phone etc.)
Above validation checklist is showing the points under which you should have validate your WordPress website. Let’s see a brief description on that point:
Validate HTML section make sure that your entire website has valid HTML code or not.
Valid CSS File:
Since CSS file is very important file to website point of view because of CSS file manages all the content of website, website layout and design and many more. So it is very important that you have to validate the CSS file. Under this section; CSS style, CSS browser specific code and many more are validated.
Validate comments or feedback plays an important role in your site because of through this section an external user could interact with your website. Under this section; special character used by user, external links of websites, abuses words and many more should have validated.
Validate Input Field Value:
Validate Input Field Value section make sure that the input field accepts legal value and validate illegal value.
This section checks upcoming links of website either it is custom (created by the admin) or simple link (submitted by the external user) are in well formed or not.
Validate install theme or custom theme:
This section validate custom theme or install theme in your website and checks it works properly or not. Validate to the external user to upload and install the theme in proper manner.
This section checks that plugin should be uploading in proper manner and checks plugin description defined in proper manner or not.
Validate URL Structure:
Validate URL structure in your website and filtered it, and match it with your custom URL structure.
Validate Categories and blog:
This section checks your categories and blog that they are proper attach with article/blog or not.
Validate to check across different browser:
This section validate to check across different browser explores, your WordPress website are working properly in different browser or not, if not then validate to it.