Forums - Part of s2 Member?

Hi,
Want to know if a "forum" is part of the s2 membership package.
Or is that something separate?
What do you recommend / what do you use?
THanks,
John
Want to know if a "forum" is part of the s2 membership package.
Or is that something separate?
What do you recommend / what do you use?
THanks,
John