Hey All!  Looking for some advice on the best way to define user groups/dept. within a customer account.

I have a few accounts that I work with that have completely separate teams for different products.  Is there a way to tag users/define users to show they are part of a group so I can easily see on the account timeline what emails, meetings, and notes are for which team? 

I did some reading on relationships in GS but I’m not sure this is what I’m looking for.  

Thank you!