Advantages of digital over analog signals

A digital signal has only a finite set of discrete levels (usually 0 and 1), while an analog signal varies continuously. Digital signals have these advantages:

1. Noise immunity: small noise does not change a 0 into a 1, so the signal is received correctly. In an analog signal, any noise directly distorts the information.
2. Regeneration: a digital signal can be fully restored by repeaters, so noise does not accumulate over long distances.
3. Easy storage: data can be stored in memory, discs and flash without loss of quality, and copied any number of times exactly.
4. Easy processing: digital data can be processed by computers and microprocessors using software.
5. Error detection and correction: parity bits and codes (Hamming, CRC) can find and fix errors.
6. Encryption and compression are easy to apply.
7. Accuracy and precision are set by the number of bits, and do not drift with temperature or ageing.
8. Design and integration: digital circuits are easy to design and fit in ICs with millions of gates, giving low cost and small size.
9. Multiplexing: many digital signals (voice, video, data) share one channel easily (TDM).

Example: a song copied many times on an audio cassette (analog) becomes noisy, but an MP3 file copied many times stays exactly the same.