???

it's an IP address (the number that identifies a computer/site on the Internet), in the format [# 0-255].[# 0-255].[# 0-255].[# 0-255] that's dedicated to your site. other times, hosts just have one or a small block of numbers assigned to a server, and that number or those numbers refer to all the sites on the server. having one dedicated to your site can be useful, for example I believe it allows you to be able to always upload to your site, even without the domain being available- such as when you first register or transfer it.

hope that made sense :P

EDIT: sorry, got my numbers wrong :P