XLR cable was created by the ITT corporation several decades ago. Despite any tales you may have heard "XLR" doesn't stand for anything. It was simply a code given to the type of cable. For example ITT also named other types of cable "QG" and "NC" which also don't stand for anything. The cable comes in many types, but specifically for audio it has three pins usually. Two pins for audio signal and the third for either ground or phantom power for microphones. The cables also come with as few as two or as many as seven pins. The connectors come in male and female form however the connectors themselves have varations ranging from rectangular chasis, to right angle plugs, to the most common straight connectors. Despite the differences all are compatible with each other.