Well temperament refers to a musical tuning system that allows instruments to play in harmony across different keys. It is a compromise between pure intervals and the need for versatility, enabling musicians to perform in various tonalities without sounding out of tune. This system is particularly important for keyboard instruments like the piano. The most common form of well temperament is equal temperament, where the octave is divided into twelve equal parts. This allows for consistent sound quality, making it easier for musicians to collaborate and perform together. Well temperament has been widely used since the Renaissance and remains a foundational concept in Western music theory.