1. Public Chat : There is a channel which can be participated by anyone without an admission.
2. Direct Messaging : 1-on-1 messaging is a private channel between two users. Basically it is same as group messaging channel with only two members.
3. Group messaging : Group messaging is a private channel between multiple users. The user who wants to join the Group messaging channel has to be invited by other user who is already joined the Group messaging channel.
*Abusing users are reported by oter users will be deactivated by SendBird Messenger Administrator.