Street magicians levitate by lifting one foot off the ground and moving it so it blocks the view of the other foot touching the pavement. By raising the elevated foot until only the obscured part remains, a street magician can make it look like they are levitating off the ground.
This illusion only works if the magician’s audience is all on one side. Since a successful levitation depends on the perfect angle, it is important for the magician to rehearse his performance or the onlookers will notice something amiss. The angle is what makes this trick difficult, but it is also what makes this trick effective for street shows. The performer can control where he is standing so the audience looks from and down the right angle. David Blaine, a famous magician, uses levitation often.
There are other ways to levitate as well. Any object that can block the view of the foot touching the ground contributes to the illusion. Magicians use wooden chairs to tall grass to block the tell-tale sign of actual contact with the ground. Another variation is to move far enough away from the audience so the foot is in shadow, and simply bring one of the legs up so it gives the appearance of floating. Other variations are done with camera tricks or wires and a winch.