Circle of fifths

From Wikipedia:

"In music theory, the circle of fifths shows the relationships among the twelve tones of the chromatic scale, their corresponding key signatures, and the associated major and minor keys. More specifically, it is a geometrical representation of relationships among the twelve pitch classes of the chromatic scale in pitch class space. Since the term 'fifth' defines an interval or mathematical ratio which is the closest and most consonant non-octave interval, then the circle of fifths is a circle of closely related pitches or key tonalities. Musicians and composers use the circle of fifths to understand and describe those relationships. The circle's design is helpful in composing and harmonizing melodies, building chords, and moving to different keys within a composition."