A V10 engine is a V-shaped engine, with five cylinders to a side. The design comes from the mating to two inline five cylinder engines. The configuration is not naturally balanced, and has a rocking motion, even though the five-cylinder designs were balanced. In most V10 designs, balance shafts are used for stability.
The first racing V10 was created by Alfa Romeo in 1986, but the engine was never actually used in competition. When turbocharging was outlawed after the 1988 season, both Honda and Renault saw the V10 as the optimal compromise between the compact V8 and powerful V12 designs.
Formula One teams who used V10 engines
Note: From 1998 to 2005, all teams used V10 engines.