Junctions between cells most occur on or very near the cell's plasma membrane, but can also involve the tiny space between cells and sometimes the layer of cytoplasm that lies just below the plasma membrane. These junctions mostly fall into three categories which depend on the function they serve.
A cell junction (or intercellular bridge[1]) is a type of structure that exists within the tissue of some multicellular organisms, such as animals. Cell junctions consist of multiprotein complexes that provide contact between neighbouring cells or between a cell and the extracellular matrix. They also build up the paracellular barrier of epithelia and control the paracellular transport. Cell junctions are especially abundant in epithelial tissues.