While you can get a general idea of racing on the iRacing.com service - such as learning your braking points - the one thing that you can't learn via testing by yourself.. is racing with others. For example, the only way you got a feel for what happens in an race is by joining an official race and learn it on the fly. Who wants to destroy their safety rating by learning on the fly though? This is where iRacing's Ghost/Spectator sessions come into play.

The ghost session allows you to join an official race or hosted session, but you are invisible to everyone in that session. You are able to see every car on the track, but none of the other drivers can see you. You can't make contact with any other drivers - but will still make contact with the barriers, walls, etc., - nor will they see any skid marks left by you, if you spin out.

Pretty much... you are not officially racing as none of the lap times are recorded, your safety rating isn't effected, and the session event isn't saved. You are a ghost. The good/cool thing about the ghost session is it allows you to learn being around a pack of cars at Talladega, or being bunched together at Bristol.. without the risk of screwing up someone's race. If you wreck, then you wreck.. but you don't lose safety rating, you just learn from the mistake you made. While you aren't making contact with other drivers, I would still race around them like you can make contact with them like any other racing. Don't go driving through the car in front of you, work on your passing and you'll be good to go for races.. where you aren't a ghost.

You can also choose just to spectate the race and watch everyone race with various camera angles. I enjoy using the spectator finish as you can find the person who is turning the fast laps and study their line, braking points, etc.

To do either of these features all you have to do is: Hover your mouse over "Events", select Spectator/Ghost Session from the list, and then select the race you want to spectate/ghost.