There are several ways, how one can access a website. Using domain name (i.e.
http//www.example.com/) is one of most popular. We can also use IPv4 address (i.e.
http://188.8.131.52/). In certain situations URL can be "enhanced" with port number, login and password etc.
A bit less known option is to access an URL using IPv6 address. You only need to enclose it inside square brackets i.e.:
Edit: Thanks to Foo Bar for correcting an obvious, yet fundamental mistake to this article.