A number-plus-letter code (1A through 12B) that maps each musical key onto a clock-face wheel so DJs can find harmonically compatible tracks without reading standard music notation.
Camelot Key Notation assigns each of the 24 major and minor keys a code from 1A through 12B, arranged in a circle so that compatible keys sit adjacent to one another. A denotes minor keys and B denotes major keys; the numbers 1 through 12 represent positions on the clock-face wheel, where moving one step in either direction (for example from 8A to 9A or 7A) yields a harmonically compatible key relationship.
Why it matters
The system removes the need for a DJ to know music theory in order to make harmonic mixing decisions. Instead of reasoning about the circle of fifths, a DJ can compare two Camelot codes and immediately know whether a transition will be safe: same code is always compatible, adjacent number same letter is compatible, and same number different letter (switching between A and B) moves between relative minor and major.
In practice
Tag every track's Camelot code in your library metadata. When selecting the next track, filter to the same code, the code one number higher or lower with the same letter, or the same number with the opposite letter. These three moves cover the majority of clean harmonic transitions.
