Vertical
Looks like it should be the simplest, but is actually one of the hardest jumps for a horse. Naturally, the horse will jump over a sloping shape and the vertical requires a steep arc. Course builders can also play with distances, putting a vertical immediately after a combination so the rider has to accelerate quickly to gain the momentum required.
Wall
Made from wooden bricks. The top bricks are loose and can be knocked off. Not being able to see through the obstacle, horses can sometimes jump wide, incurring time penalties.
Oxer
Two or three parallel fences with space between them to create depth as well as height. The horse needs to make the highest part of his jump in the centre of the fence. A square oxer is when both fences are the same height.