As long as the ball is touching the line, it is considered in. Even if the majority of the tennis ball is out, as long as a tiny sliver of that tennis ball is touching the line, it is considered in.
When the ball hits the tennis racket, topspin (preffered stroke of tennis) makes the ball spin. The upward motion of the racket hitting the tennis ball.
yes
On the serve, it must be in the service box. Other shots will depend what type of tennis you are playing. In doubles the boundaries are the most outward side lines and the baseline. In singles it is the innermost sidelines and the baseline
Yes. If any part of the ball hits any part of the line, it is considered in.
Let
It is called a "let" in tennis when the ball hits the net because "Filet" is the French word for net and the game originated in France.
If the ball hits the line then the ball is called in. But if its even a little bit over the line then its out and the other team gets the ball.
No
a ball only when it hits the ground though.
If the ball touches the line, it's considered fair play or in bounds.
In Table Tennis, as long as the ball touches the table, it is counted, the markings aren't important.