Athletes with two oars -- one in each hand -- are scullers. There are three sculling events: the single -- 1x (one person), the double -- 2x (two) and the quad -- 4x (four).
Athletes with only one oar are sweep rowers. Sweep boats may or may not carry a coxswain (pronounced cox-n) to steer and be the on-the-water coach. In boats without coxswains, one of the rowers steers by moving the rudder with his or her foot.
Sweep rowers come in pairs with a coxswain (2+) and pairs without (2-), fours with a coxswain (4+) and fours without (4-) and the eight (8+), which always carries a coxswain.