Device used with record players that holds the stylus or needle and attaches to the tonearm of the record player converting signals from the record grooves into electrical energy that can be played on an audio system. record player works by placing a very small metal shaft (the stylus or needle) into the grooves on the record itself. The turntable (a rotating platter the record sits on) rotates the record while the stylus sits in the grooves. The record grooves contain the audio signal in the form of small waves or hills and valleys inside the grooves. The stylus moves up and down in these waves. s the stylus moves, it creates a magnetic field in the cartridge holding it (this process is the reverse of a speaker driver). The stylus moves in relation to the cartridge resulting in a magnet moving through a coil of wire (moving-magnet design) or a coil of wire moving inside a magnet (moving-coil design). In either case, a magnetic field is created by the coil and magnet interaction creating an electric signal (a varying electric voltage) in the coil. he coil is connected through wires to the output of the record player where it can travel to a preamplifier and then on to the amplifier and finally to the speakers. The cartridge plays the vital role of holding the stylus or needle in the grooves and generating the electric signal needed to pass the signal along and reproduce the sound.