Depending on your home brewing setup, you may need to transfer your beer from one place to another with a beer pump.  We have two different styles of pumps - a self-priming and a magnetic drive pump.  The self-priming pump is for cool, uncarbonated beer ( coming out of a fermenter). What does self-priming mean?  A pump that is not self-priming will not suck air and must be fed liquid via gravity before it will begin to pump.  The pump head and lines must be full before the pumps is started. A pump that is self-priming will pump air and therefore can create a suction that will draw liquid out of a vessel. 

The March magnetic-drive brewing pump is the most widely used pump by homebrewers.  Why? - because it is magnetc driven, you can put a ball valve after the pump to slow down flow without burning out the motor. Mag drive pumps are used for hot liquid transfers - when sparging or recirculating.