Complex sentence: A race track (or'racetrack' or'racing track') is a purpose-built facility for racing of animals (eg. horse racing or greyhound racing), automobiles, motorcycles or athletes.
Split into simpler sentences: A race track (or'racetrack' or'racing track') is a purpose-built facility for racing. This racing can be of animals (eg. horse racing or greyhound racing), automobiles, motorcycles or athletes.