Email validation checks the following points Figure 2: Above two figures are example of valid and invalid emails.
If you have such a form on your site, I'm sure that from time to time, you would have received the results of your form with some essential field (like the email address or the visitor's name, or even the feedback itself) omitted. One way around it is to validate the essential fields with a simple Java Script.
These pages will show how to process PHP forms with security in mind.
Proper validation of form data is important to protect your form from hackers and spammers!
For example, you can have an input field that should not be empty, should be less than 25 chars and should be alpha-numeric. In some dynamically programmed pages, it may be required to change the validations in the form at run time.
In other words, in order to validate a field, you just associate a set of validation descriptors for each input field in the form. For such cases, a function is included which clears all validations in the validator object. Note that this validation if for fields like Textbox and multi-line text box.