A
node is a point along a
standing wave where the wave has minimum
amplitude. For instance, in a vibrating
guitar string, the ends of the string are nodes. By changing the position of the end node through
frets, the guitarist changes the effective length of the
vibrating string and thereby the
note played. The opposite of a node is an
anti-node, a point where the amplitude of the standing wave is a maximum. These occur midway between the nodes.