A sub-team is a team within a team. A Team Owner can create a sub-team to collaborate on projects that may not involve the entire team.
For example, if you and a few other members from the marketing team are working on a project with an outside contractor, you can create a sub-team and:
1. Click the gear icon next to the team name.
2. Click Create sub-team
3. Remove team members you do not want to include in the sub-team. If you like, add other people to the sub-team.
4. Set the privacy level for the sub-team (Pro feature).
5. Click CREATE SUB-TEAM.