In a video wipe, one shot is progressively replaced by another shot in a geometric pattern. There are many types of wipe, from straight lines to complex shapes.
Wipes often have a coloured border to help distinguish the two shots during the transition.
Split-screens often use a wipe. A horizontal line wipes from left or right into the middle of frame, revealing the new shot in that half.
Wipes are a good way to show changing location or viewpoint.