An indoor rower, or rowing machine, is a machine used to simulate the action of watercraft rowing for the purpose of exercise or training for rowing. Modern indoor rowers are often known as ergometers (colloquially erg or ergo) because they measure work performed by the rower (which can be measured in ergs). Indoor rowing has become established as a sport, drawing a competitive environment from around the world. The term "indoor rower" also refers to a participant in this sport.