A node is a spatial locus along a standing wave where the wave has minimal amplitude. This has implications in several fields. For instance, in a guitar string, the ends of the string are nodes. By changing the position of one of these nodes through fretwork, the guitarist changes the effective length of the vibrating string and thereby the note played. The opposite of a node is an anti-node.

There are two kinds of nodes in standing waves.

• Displacement node– minimal amplitude
• Pressure node– minimal pressure; occurs at a diplacement antinode