A comparator is a combinational device that sorts two keys. Namely, it has two incoming edges and it receives a key from each one of them. It has two outgoing edges of distinct types; a min edge and a max edge. It transmits the minimal key on the min edge and the maximal key on the max edge. Clearly, a network has the same number of input edges and output edges. To specify how an input sequence should be fed into the network, the input edges are arranged as a sequence. Similarly, the output edges of a network are arranged as a sequence to specify how the network’s output is interpreted as a sequence. The notion of a network implies nodes and links. The nodes can be people, teams or even organizations - networks operate at many levels. Common examples are distributed geographic teams in large organizations, or small organizations operating as networks to compete against large corporations. The links are the various coordination and "agreement" mechanisms. In a network, high degrees of informal communications (both face-to-face and over electronic networks) achieve success where formal authority and communications in hierarchical organizations often fail. Two way links and reciprocity across the links are what makes networks work.