The act or practice of recording anything by marks, figures, or characters.
Any particular system of characters, symbols, or abbreviated expressions used in art or science, to express briefly technical facts, quantities, etc. Esp., the system of figures, letters, and signs used in arithmetic and algebra to express number, quantity, or operations.
Imagine someone so infatuated by a band that they have every different pressing of every album the band made. Most of the time, the only difference in the album is the matrix number or a different 'made in' notation on the back cover or label. This is enough to make some people extremely excited. Actually, much more than excited. Henry Rollins