What does MySQL "::1" hostname refer to?

On a freshly installed (windows version of) 开发者_运维知识库MySQL 5.5.9

SELECT user, host FROM mysql.user

gives:

user            host    

root        localhost   
root        127.0.0.1    
root        ::1  
localhost    

But what IP/hostname does ::1 stand here for?

::1 is the IPv6 address for localhost.

The details (incl.those relevant to the Windows case) are at http://dev.mysql.com/doc/refman/5.5/en/default-privileges.html.