When you restrict the values that users can enter in forms, you reduce the chance that someone can enter a value that can compromise the security of your site.
To see how validation works, run this page and deliberately make mistakes.
Therefore, you also have to make sure that the values that users enter can be correctly converted to the appropriate data types.
You might also have certain restrictions on the values.
Users get immediate feedback, which is convenient for them.For example, if a page has an element as a placeholder for an individual field error, even if there is no error.In some situations, displaying an error message can cause the page to reflow and can cause elements on the page to move around.Performing validation in server code is a security measure, in case users bypass client-based validation.In this example, the test for a valid date won't work in client code.
The CSS rules that end in to both have the same fixed size.