Sample php function to check the email address whether it is valid or not.
Paging is one of the essential feature for data driven website to implement. Whenever user search in the site, there may be thousands of results for the keyword what he/she search. Of course, you could show all results on one page. But it will slow down the loading of your page and user may leave your page. So it is better to split the records into pages with a certain number of records per page.