"MASTERING" IS DONE IN THE PRODUCTION OF CD'S, CASSETTES AND L.P. RECORDS. BACK IN THE DAYS OF MANUFACTURING VINYL RECORDS, PART OF THAT PROCESS INCLUDED PRODUCING ("CUTTING") A METAL LACQUER MASTER, OR ACETATE, WHICH WAS SHIPPED TO A PRODUCTION PLANT (THUS THE ORIGINATION OF THE TERM "CUTTING A RECORD"). MASTERING WAS TYPICALLY DONE AT A MASTERING STUDIO, (OR LARGE RECORD LABEL RECORDING STUDIO) AND CONSIDERED THE LAST "ARTISTIC" PHASE IN THE PRODUCTION PROCESS, BECAUSE THERE WERE NUMEROUS ADJUSTMENTS THAT COULD BE MADE, SUCH AS E.Q., COMPRESSION, SEQUENCING, ETC. ONCE THE PLANT GOT THE MASTER, THEY MADE A NEGATIVE, A STEEL POSITIVE, AND THEN A "STAMPER". YES, THIS IS THE ACTUAL ACETATE COATED METAL "PRODUCTION PARTS" THAT ARE CUT ON A LATHE AND SENT TO THE PRESSING PLANT TO MAKE THE STAMPERS THAT ARE THEN USED FOR PRODUCING VINYL RECORDS. THEY PLAY JUST LIKE A RECORD, THOUGH, AND I SUSPECT ARE MORE DURABLE DUE TO THEIR MATERIAL (THOUGH I COULDN'T SAY FOR SURE).