A set with two elements, often with an order explicit in it, such as the coordinate pair (x, y), which would be referred to as an ordered pair. So, as ordered pairs (1,2) ≠ (2,1) but as sets {1,2} = {2,1}. SeeCartesian product.
Electronics and Electrical Engineering
A transmission line consisting of two similar conductors that are insulated from each other but are associated to form part of a communication channel or channels. If the two conductors are twisted around each other they form a twisted pair. Many pairs can be further twisted together. The twisted pair or pairs can be inside an earthed conducting shield, usually formed from braided fine wire mesh, to minimize electromagnetic interference; this is a shielded twisted pair (STP) construction. In an unshielded twisted pair (UTP) construction, the twisted pair(s) are uncovered or bundled within an insulating PVC covering. A coaxial pair is a pair of cylindrical conductors that are coaxial and may be used to form a coaxial cable.