If your net has Auto-CheckIn enabled, attendees are checked in automatically as soon as they arrive online. This allows for a very streamlined process, as the net can just focus on the content and not consume unnecessary time with a lengthy check-in process.

On occasion attendees may show up and their preference is to just "monitor" or be a "lurker"..they don't want to check-in. If this happens, use the "ui" command to un-check them in. This will make them appear as a lurker.

Some nets opt to highlight station rows associated with lurkers, rather than use the ui command. My recommendation would be to use the ui command, so that the highlight command can be used to denote other things....  My 0.02.