A 78 is simply a record that is played at 78 rotations per minute, or r.p.m’s. First introduced in 1887 by Emile Berliner, it didn’t become commercially viable until the early 20th century, when it became a valid competitor to the more popular wax or celluloid cylinders. At first there was some variance in the speed; discs could play back at a range of 75-80 r.p.m’s, depending on the manufacturer. By the 1920‘s, 78 r.p.m’s had become the industry standard. The discs were usually 10 inches wide and made from shellac—or by the 1930s, synthetic shellac—making these discs heavier and more brittle than their later vinyl counterparts. 78s weren’t really called 78s until the late 1940s, when long-playing records that were played back at 33 r.p.m’s came onto the scene and created the need for the distinction.