Post numbers in a thread

[Bean Kenobi]

Hi,
I often see members saying "see post number xx" while reading a thread.
I searched but couldn't find any such number.
Where do you find it ? Has it to be activated somewhere to be displayed (not "by default" ?).
Thanks a lot.

[StraumliBlight]

[Bean Kenobi]

Oh yes, and I never saw it before... thanks !