A cellular component that forms a specialized region of connection between two or more cells or between a cell and the extracellular matrix. At a cell junction, anchoring proteins extend through the plasma membrane to link cytoskeletal proteins in one cell to cytoskeletal proteins in neighboring cells or to proteins in the extracellular matrix. [ https://www.worldcat.org/search?q=bn%3A0198506732 http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/junctions_a.html ]