How did equal temperament help composers use all 12 chromatic notes freely?

Equal temperament enabled composers to use all 12 chromatic notes freely by resolving the limitations of earlier "cyclic" tuning systems, such as meantone temperament, which were designed for specific keys and became increasingly dissonant as music moved into more distant keys.12

In previous systems, fixed-pitch instruments like the keyboard could not reconcile enharmonic equivalents—for example, a single key had to serve as both E♭ and D♯. When a composition required a note outside the instrument's limited tuning, it produced a severe dissonance known as the "wolf".23

Equal temperament solved this by dividing the octave into 12 semitones of equal size, each measured at 100 cents. By distributing small intonational defects equally across all 12 tones, the system ensured that intervals remained identical in every key. This uniformity allowed composers to modulate freely and utilize the full chromatic scale without encountering the "wolf" intervals that restricted earlier harmonic exploration.12