One foot -- two feet.
Dribble or catch a pass, and the player's footstep is in motion, he can take the ball when he finishes the dribble, then jump on one foot, and finally both feet fall simultaneously. This is the jump in most cases.
One foot -- one foot.
Still dribble or catch a pass and move. When he finishes the dribble, he can take the ball, jump on one foot and land on one foot (note: this one foot can be a one-foot).
A1 movement ended in dribbling, for example, he has the ball left foot jump, then fall to the ground, his final shot or pass (this is the so-called "three-step layup, depressed, is actually a coherent ball run two step).
For example, A1 runs out of the dribble, he takes the ball off his left foot, then he lands on his left foot, and he still shoots or passes in the air with his left foot. This is similar to the triple jump in track and field, but the rules allow only two levels.