HTML Forms are used everywhere on web - for creating an account, for submitting applications, for submitting payment information, etc. In this tutorial you will learn how to read HTML form data from JavaScript and how to perform form validation (that the user has filled the form as expected).
Note: Once the form has been filled satisfactorily by the user and submitted, often the information is sent to server (the computer which responds to user requests for your website) or stored in your database. For example, if the user just entered his log-in details, this data is sent to the server, which responds back saying whether the log-in credentials were correct or not. We'll cover such interactions (making web-requests from JavaScript) later in the course.