Digital information is stored using two discrete values, while analog information is typically stored using nondiscrete signals. Since the advent of digital technology, the term "analog" has been used to refer to nondigital storage and transfer technology.
A common example of analog information is vinyl records. Peaks and valleys on an album represent different sounds, and the player's needle responds when the record spins. Cassette tapes, another form of analog information storage, rely on a magnetized medium, and stronger and weaker magnetic signals represent different sounds.
Digital technology uses two values, often referred to as 1 and 0, to store information. These signals can be stored as magnetized and nonmagnetized regions on a hard drive; they can also be stored as microscopic grooves on CDs. Many media used to store analog information can store digital information as well. Tape backup devices, for example, use technology similar to cassette tapes to store the 1s and 0s used for digital information.
One of the primary advantages of digital technology is that information can be preserved and copied perfectly. Many analog media degrade over time, and quality invariably drops when information is copied. Digital information can also be sent over computer networks and the Internet, which has contributed to the widespread popularity of digital information. In addition, digital information can be compressed, so it takes up less space and transfers faster.