System message This option allows to you see or hide "user entered room" and "user left room" messages.Block users This is the list of members you have blocked and you can unblock them from here.
Font size Font size option allows you to change chat font size.
Mention Mention allows to mention a member in your message and it will appear highlighted to them.
Whisper After typing your message, selecting "whipser" option will send your message as a whisper.
Right side will show list of members who are present in that room.
Clicking a members names in the right side list will show the "user options" as shown in the image above and each option is explained below.
Some chat rooms may only be available to registered members.