How do I create a chat group?

To create a chat group, navigate to the Chat tab > tap the Blue + button > select Create a group. Give your group a name and decide whether you'd like it to be Broadcast only and / or Public by toggling those options as desired. Once done, tap Save changes to create your group.

As an Admin, you can change the name of your group and whether or not it is Broadcast only at any time in the group's settings, which can be accessed by tapping the group's name at the top of the conversation feed. That said, whether a group is Private or Public cannot be changed after group creation.

Fedi chat groups are private by default, meaning that messages sent in the group are end-to-end encrypted (E2EE) and can only be read by individuals who are members of the group before a given message is sent. 

When you join a private group, messages that were sent prior to you joining are represented by a blurb that reads "This message is private." Despite running the Matrix chat servers, not even Fedi can read messages sent in private groups.