Originally Posted by
UGBSM
Pilots use a CTAF to communicate with each other and coordinate their movements. UNICOM, on the other hand, is more like a customer service desk at the airport. CTAF is usually the tower frequency, and UNICOM exists specifically to keep that sort of traffic off the tower frequency.
Exactly. UNICOM at large airports is usally monitored by the FBO(s) and is used to arrange fuel and parking and passenger pickups etc. This is not the same as CTAF and every professional pilot should know this.