A chord, simply, is any combination of notes. Theoretically, any combination of notes is a chord, however, when used in a certain combination, some notes complement each other better than others. These notes are played together the most often, and make up the most popular chords. Traditionally, chords used three notes. While two notes is technically harmony, they can also be considered chords in general. Because of the broad nature of this definition, types of chords have been developed that "sound good", in the western philosophy of music.
The following chords can be played in any scale. To understand them, one should have the basic knowledge of a scale first. There is no specific tonal order for the notes to be played; many kinds of "inversions" can be created by placing the notes in different orders. The first four examples are shown with the root note C. The remaining examples listed here are shown with the root note Bb.