If you step on the white line in front of you while serving, it is illegal, its called faulting
Yes!
yes
A fault.
Yes, this false start, along with serving with your racket above your waistline and moving your foot forward during the serve is illegal. You serve with one movement and one breath, basically. Any attempt to throw the receiver off is an unfair play, especially at the start of a game.
Almost all of your joints are used in tennis, but the main ones in a tennis serve are the knee joints, and elbow joints.
It's illegal to serve a minor ANYWHERE
You can hit an underhand serve in tennis; however, the overhand serve is more effective because it is more powerful. That is why you don't see the underhand serve used much.
a serve
Badly.
A tennis ball!
a tennis ball
Let
Yes
A tennis ball.