1. Resources (in computing usually processing time or storage
space) consumed for purposes which are incidental to, but
necessary to, the main one. Overheads are usually
quantifiable "costs" of some kind.
Examples: The overheads in running a business include the cost
of heating the building. Keeping a program running all the
time eliminates the overhead of loading and initialising it
for each transaction. Turning a subroutine into inline
code eliminates the call and return time overhead for each
execution but introduces space overheads.
2. <communications> information, such as control, routing, and
error checking characters, that is transmitted along with the
user data. It also includes information such as network
status or operational instructions, network routing
information, and retransmissions of user data received in
error.
3. Overhead transparencies or "slides" (usually 8-1/2" x 11")
that are projected to an audience via an overhead (flatbed)
projector.
