All sites experience some degree of link failure or misuse. For example:
Typically the user will see an unhelpful error message. By customising the HTML files in the error directory of your hosting you can display a more relevant error message themed in with your website.
The names of the error HTML files must not change, if they do then no error page will be displayed.
Custom error pages are frequently used on websites where pages and links are constantly being updated and removed. The most common error page is the 404 file not found. There is a whole website devoted to 404 error pages with archives 404 pages www.plinko.net/404/.