Melody represents the horizontal aspect of music; it consists of tones that are sounded one after another in a linear fashion. Harmony, on the other hand, involves the vertical aspect of music; that is, tones of different pitch that are sounded together. Technically, harmony is defined as the simultaneous combination of two or more sounds.

The  first movement of the Violin Concerto No. 1 by Max Bruch contains many examples of melody and harmony used in different ways. Listen to the first exchange between the orchestral harmonic progression, which establishes the tonality of the piece, and the entrance of the soloist's melody. Although the violin is usually referred to as a melodic (one note at a time) instrument, it is also capable of playing more than one sound at a time. Listen to this magnificently performed passage, in which the violinist combines single notes and chords—a technique called double stops in string performance—to play the main theme of this movement.