Any plug and socket that links two devices together. Although taken for granted and rarely in the limelight, connectors are a huge industry, and the quality of these components is more critical than most people would imagine. When not designed or constructed properly, they often become the weakest element in an electronic system. See CLINKS
In database management, a link or pointer between two data structures.
In flowcharting, a symbol used to break a sequence and resume the sequence elsewhere. It is often a small circle with a number in it.