Complex sentence: In sports where goals are the sole method of scoring, the goal is often a rectangular structure set at each end of the playing surface, consisting of two vertical posts, called the goal posts, supporting a horizontal crossbar.
Split into simpler sentences: In sports where goals are the sole method of scoring, the goal is often a rectangular structure that is placed at each end of the playing surface. Each structure usually consists of two vertical posts, called the goal posts, supporting a horizontal crossbar.