I see some website URLs have hash values attached to them. Is this for security reasons? If so, how do we benefit from that approach?

example: h-t-t-p://w-w-w.mysite.com/forums/search/results/3400faebf7f6e0b549751ca029026a61/


if you mean by a url such as http://www.site.com/index.php#hello

then in your page an element will be named hello. when you click on such a link then the page will be redirected to that link and the page will be centered at the element hello.

Sometimes those hash values, prevent page caching in the browser, other times it is just a generated page name (for example for a particular combination of search conditions).