Search your site
As the pages on your website grow to a considerably high number, so is the time that is required to locate a page. Visitors do not have the patience to browse all the pages just to find what they are looking for. Therefore, it is quite obvious why any website with reasonable page volume should have a search functionality of its own.
I know most of you do not want to hassle themselves dipping fingers in actual coding of the functionality. You do not actually need to do that because there are always third parties: what they will do is to provide you the code and you will just have to install the code to your website. Easy, eh?