A Ghostbuster is a person or even in a few cases a spirit itself that performs duties of removal of a spirit (aka: ghost, apparition, the undead). Officially the Ghostbusters are paranormal investigators, not ghosthunters. Catching ghosts just happens to be their primary form of business. Sometimes removal doesn't mean through means of weapons as a spirit may leave due to fulfillment, being remembered, or destruction of an object attaching them to this world. However, most hauntings are of unhappy spirits, and like humans may have negative reasons for being there.
What does a ghostbuster do?
In the Ghostbusters universe a ghostbuster will at the request of a client come to the scene of a possible haunting and investigate the scene. The use of a P.K.E. meter will be used to detect a spirit. Ecto-goggles or a Ghost Sniffer may also be used.
After the spirit is found the ghostbusters will use a Proton Pack with a proton gun to blast a ghost to get them under control. This may require more than one ghostbuster to do. Then the Trap is thrown near the ghost and then activated. This will suck the ghost in the trap. After the ghost is trapped, it is then dumped into the larger Containment Unit.
Some ghosts are too powerful or weak to trap and can only be destroyed.