If a ball touches a line, it is considered to be the same as hitting the space inside that line.
During the service motion, a server may not:
- Change position by walking or running. Although slight movements of the feet are allowed.
- Touch the baseline, or the court, with either foot.
- Touch the area on the other side of an imaginary extension of the sideline.
- Touch the imaginary extension of the center mark with either foot.
If the server commits any of these actions, a foot fault may be ruled.