In music theory, a minor second is an interval that has only one half steps 
The minor second requires that:
- The interval must be a second interval (two note names between the first and the last).
- The interval must have only one half steps.
What does a minor second look like?
Here is an example of a melodic minor second (two music notes in a melody) and a harmonic minor second (in a chord):
How to recognize a minor second?
Rule of music theory: All intervals in a major scale starting with the tonic (degree I) are either major or perfect, and only unison, octave, fourth and fifth are perfect (the others are major).
Example with the interval G / A♭:
Let's take the G major scale to have G as the tonic:
From the rule stated above, the interval G / A is a major second, so the interval G / A♭ is a minor second.
Inversion of the minor second
The inversion of the minor second is the major seventh.
Here is an example of a major seventh:
Musical examples of minor second
Main Title from "Jaws" Soundtrack by John Williams
One of the most famous examples of the use of minor seconds is the music by John Williams for the film Jaws:
Dvorak Symphony No.9, fourth movement
The above example of Jaws soundtrack is reminiscent of the beginning of the fourth movement of Dvorak's Symphony No.9:
Beethoven, Für Elise
Bagatelle No.25 in A minor for solo piano By Beethoven, known as "Für Elise", also has many minor seconds:
Interval identification game
You will find this interval in my Intervals identification game:
