Analog vs. Digital: What's the Difference?

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An analog signal varies continuously and can take any value within a range, like the smoothly changing voltage from a microphone, while a digital signal represents information as discrete values, usually just two levels standing for 0 and 1. Digital signals resist noise and copy perfectly; analog signals capture continuous detail directly but lose a little quality with every copy and transmission.

At a glance

	Analog	Digital
Values	Continuous: any value within a range	Discrete: usually two levels, 0 and 1
Waveform	Smooth wave, such as a sine wave	Square wave with sharp steps
Effect of noise	Noise adds directly and builds up	Small noise ignored; signal can be regenerated
Copying	Each copy loses a little quality	Copies are exact
Examples	Vinyl record, mercury thermometer, FM radio	MP3 file, digital thermometer, Wi-Fi

Which should you use?

Analog

Analog describes quantities in the natural world, such as sound pressure, temperature and light, and circuits that handle them directly, like a microphone and amplifier feeding a loudspeaker.

Digital

Digital is used for storing, processing and sending information reliably, such as a phone turning your voice into numbers so a call or voice note crosses long distances without added hiss.

Frequently asked questions

How is an analog signal converted to digital?

An analog-to-digital converter (ADC) samples the signal at regular intervals and rounds each sample to the nearest of a fixed set of levels. Music CDs, for example, take 44,100 samples per second, each stored as a 16-bit number.

Is a clock with hands analog or digital?

A clock with hands is analog in display, because the hands sweep around a continuous dial, while a digital clock shows time as numbers that change in discrete steps. The words describe the display; many analog-faced clocks have digital quartz timing inside.

Why did TV and radio move from analog to digital?

Digital broadcasting fits more channels into the same radio spectrum by compressing data, and error correction keeps the picture clean until the signal gets very weak. Analog signals use more bandwidth and show snow or hiss as reception worsens.