HTML5, CSS Validation

Before you put anything online you should validate your code to ensure that there isn't any mistakes.

To do this you go to http://validator.w3.org/

This is mainly for HTML, XHTML, XML and HTML5.

Once here you should upload your file onto the website and hit validate, once you have done this it will pick up any mistakes within your code.

You must always ensure you do this otherwise, you might be putting broken code on to the web.

You are able to validate your CSS using http://jigsaw.w3.org/css-validator/validator

The same applies for this one as the HTML validator, you upload your file, and it will check for errors.