In response to either infection or immunization with a foreign agent, the immune system generates many different antibodies that bind to the foreign molecules. Individual antibodies within this polyclonal antibody pool bind to specific sites on a target molecule known as epitopes. Isolation of an individual antibody within the polyclonal antibody pool would allow biochemical and biological characterization of a highly specific molecular entity targeting only a single epitope. Realization of the therapeutic potential of such specificity launched research into the development of methods to isolate and continuously generate a supply of a single lineage of antibody, a monoclonal antibody (mAb).