When two waves traveling in opposite directions through the same medium collide, the amplitude of the resulting wave will be the sum of the two initial waves. The resulting wave will be larger than the original waves. The highest point of a constructive interference is called an antinode .
Destructive interference is when the amplitudes of the initial waves are opposite.
The amplitude of the resulting wave will be zero. The point in the middle of a destructive interference is called a node and it never moves.