What are curves in table tennis?

Answer 1

Balls or hits that are spun in the air curve through the air depending on which way they are spun.

In good Table Tennis, most shots will have various directions and elements of spin imparted to them, especially topspin.

Spinning balls moving through the air curve as a result of what is called, "the magnus effect" - where, due to the clash of the air that hugs the ball as it spins and the oncoming air through which the ball is travelling, greater air pressure is built up on that side of the ball and a 'lift' is imparted to the ball that reults in a turning or curving path of the ball through the air. Ready examples of this are the "bending" of a soccer ball that is kicked so as to impart spin on the ball and the Golf ball lift that allows the ball to travel further through the air as it is hit with underspin.