Garbage collection is
computer-science techspeak for a particular class of strategies for
dynamically but transparently reallocating computer memory (i.e., without
requiring explicit allocation and deallocation by higher-level software).
One such strategy involves periodically scanning all the data in memory and
determining what is no longer accessible; useless data items are then
discarded so that the memory they occupy can be recycled and used for
another purpose. Implementations of the LISP language usually use garbage
collection.
In jargon, the full phrase is sometimes heard but the
abbrev GC is more frequently used because it is
shorter. Note that there is an ambiguity in usage that has to be resolved
by context: “I'm going to garbage-collect my desk” usually
means to clean out the drawers, but it could also mean to throw away or
recycle the desk itself.