The two types of scales commonly used

Simultaneous sounding of three or more pitches (notes)

A sequence of pitches

A single, sustained tone sounded against a goup of tones (melody)

The 1st + 8th degree of a scale

A combination of tones that sound "discordant", unstable, in need of resolution

Harmonic organization around a central tone

The simultaneous events in music (two or more notes)

A combination of tones that provide a sense of relaxation + stability