Each K. number consists of a letter K, followed by a number. The numbers are assigned in chronological order, based on the date of composition of each work. The first work in the catalogue is K. 1, which is a Minuet in G major for piano, composed in 1762, while the last work is K. 626, which is the Requiem in D minor, composed in 1791.
The Köchel catalogue is not only a chronological listing of Mozart's works, but it also provides additional information about each work, such as the title, date of composition, instrumentation, and key signature. The catalogue also includes a brief description of each work, and often references to other editions or arrangements of the work.
The Köchel catalogue is an essential resource for scholars and musicians who study and perform Mozart's music. It is the definitive catalogue of Mozart's works, and provides valuable information about the development and evolution of his musical style.