A minor second is a musical interval between two notes that are adjacent and one half step apart. It is also referred to as a half step or a semitone. There are several synonyms for this interval, including flat second, diminished second, and diatonic semitone. Additionally, in some musical traditions, the minor second is called the augmented unison or the microtone. Regardless of the name, this interval is commonly used in music to create tension and dissonance, leading to resolution and harmony. The use of minor seconds is especially prevalent in jazz, blues, and contemporary classical music.