In telecommunication, the term has the following meanings:
- In a communications switch, a state or condition that occurs when more subscribers attempt simultaneously to access the switch than it is able to handle, even if unsaturated.
- In a saturated communications system, the condition that occurs when an additional demand for service occurs.
In medicine and pathology the term is used to describe excessive accumulation of blood or other fluid in a particular part of the body.
See the traffic congestion article for a discussion of congestion in transportation.
In electric power transmission it means the inability to supply an area with the cheapest available generation due to a binding constaint on the point to point transmission route. Some plant or equipment could be causing the constraint due to thermal overload or security limits being potentially breached.