HTML Forms have many usages, ranging from a simple contact form to a way to collect and edit data in a web-based application. Forms can be created as a static section of HTML or it can be dynamically generated with PHP based on a set of data from a database or another source. No matter how the form is generated it's good practice to validate the input before the form is submitted. This will help prevent data errors and the user will be able to correct errors without having the data sent to the server for validations. It is also necessary to validate the contents of the POST request before data is inserted into the database or otherwise used on the server.