Descriptive of a continuous wave or signal, such as that produced by varying electrical voltage, as opposed to digital, which refers to discrete numerical values. Analog signals—such as music, for example—can be converted to digital form (as in the production of a compact disc). Digital signals—such as computer output—often must be converted to analog signals (as in the transmission of data over telephone lines or in the conversion of electro-optical signals to digital information in scanning).
The term analog is also used to describe a computer using continuous signals of varying intensity, rather than the "on" or "off" dichotomy utilized by digital computers.