No you don't have to in fact, former French Open champion Michael Chang often resorted to the underhand serve. But the overhand serve is greatly recommended as more power is achieved when hit overhand.
jump serve or topspin serve
Drive serve: very hard and low serve.Z-serve: Bounces of the front wall and one side wall before landing in the receiving area at an angle.Lob serve: comes in high off the wall and is difficult to play if hit properly.
overhand serve is when you throw the volleyball directly in front of you then lift your arm up hit the center of the ball with as much force as possible
In volleyball, the main types of serves are the underhand serve, overhand serve, and jump serve. The underhand serve is the simplest, using a swinging motion to hit the ball with one hand from below. The overhand serve involves tossing the ball into the air and striking it with one hand, allowing for more power and spin. The jump serve combines a jump with an overhand hit, adding speed and unpredictability to the serve.
An underhand serve (rather than overhand traditional serve)
of course you can!. . .
underhand, overhand, and jump serve
Two ways to serve are underhand and overhand. To serve underhand, hold the ball in one hand and hit it upward with the other fist or forearm, so the ball flies in a parabola into your opponents' side of the field. To serve overhand, toss the ball above your head and then smack it with your wrist, palm, or fingers to send the ball over the net in a parabola flatter than the underhand serve.
If you cannot get behind the ball, the you should overhand pass. But most likely, if you are in backrow, the ball may be out.
There are two ways to define the terms SIDEARM in volleyball.Is a serve which is lie an overhand serve but it was a serve before and overhand serve was invented. You basically Take the ball and put it in your throwing hand for an overhand serve. Then turn your whole body sideways. Then hit the ball out of your hand that the ball is currently in.another sidearm to some people is when you go and dive or hit a ball with one arm. It can be called a sidearm but it is mostly called a one-arm hit.Hope this info helps.
The better your torque is the better contact you make with the ball when you overhand serve.
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.