This article is from the Formula One Motor Racing FAQ, by firstname.lastname@example.org (Mitchell McCann) with numerous contributions by others.
Jump starts and pit lane speeding incur a 10 second 'stop-go'
penalty. Penalties are served in the team's own pit under the
supervision of the team manager. If the team does not administer
the penalty correctly and the driver leaves before the 10
seconds is up, then they will be called back for another 10
second penalty. The officials monitor the length of the stop by
means of the timing sensors buried in the pit box. They also send
an official onto the pitlane wall to ensure that no work is done
to the car during the stop.
Other offenses can incur fines, loss of points, disqualifications
or race bans. Decisions can be appealed but historically the FIA
has a propensity for increasing a penalty on appeal.