The shortest possible distance between two notes on a piano.
A distance of two semitones
12 semitones. The distance you travel to reach the closest note that is the 'same' note but higher or lower.
The keyboard is made up of repeating sets of 12 notes. The 7 white notes are given the letter names A, B, C, D, E, F, G
The 12 notes are shown highlighted here with 'A' on the left
If the word 'sharp' (or symbol '#') is added to a note name, it means the note one semitone above the note named. For example C#
If the word 'flat' (or symbol '♭') is added to a note name, it means the note one semitone below the note named. For example B♭