When you open the app you are part of a chat room instantly. This chat room only consist of the people close to you. Every message that you type in that room stays in that room.
Your current room feels quiet? No problem. Check what is happening in other rooms (anywhere in the world). Rectangle shows you the room boundaries.
Found a interesting room? Great! Get instant notifications any time somebody writes to this room.
Now be careful. Never type your phone number in the chat as it is visible to anybody who visits this room. But what if you meet someone? Send a phone number request.

Oh yeah. Also, remember to have fun!