The Teams Chat feature creates a private conversation between you and an individual or a group. The individual/group members do not have to be on any of the Teams you belong to.

You can start a chat with others in this section by choosing a contact from the Recent or Contacts sections, or by clicking the New Chat icon.

You can also start a voice or video chat from this section. Icons for voice and video chat appear in the top right once you have initiated a chat with someone.