Thomas Edison made early phonographs in the 1870s. He originally used tin foil to record the sound. Soon wax cylinders were used in place of the tin foil. The cylinders could be taken off the machine and put back on without destroying the recording. Although discs were made as early as 1888, it was not until 1902 that discs became more popular than cylinder records. Discs were first made of a shellac mixture, and later of polyvinyl chloride, often abbreviated as "vinyl". Singles usually carried only one or two songs or recordings. EPs (extended play records) carried from three to five songs. Albums carried many more recordings; a dozen was normal, or from 30 to 45 minutes of playing time. These formats are still used today, with digital recordings, and playing time for singles and albums has grown considerably.