When Alexander Graham Bell invented the telephone in 1876, it consisted of a microphone and a speaker. Electrical signals were being pushed through wires, which have resistance, causing some of the energy to be lost as heat. This means that the further the line went, the quieter the call.
To compensate, analog amplifiers (yes, this telephone was analog!) were applied to the line to boost the signal. However, this also meant that noise electrons were amplified, and couldn’t be separated from the desired signal. As a result, both signal and noise were amplified, producing a loud sound but with extreme static.
The digital telephone approaches this issue differently. It picks up noise the same way that the analog telephone does, but differentiates in its ability to separate the noise from the signal. An analog to digital converter, or ADC, converts the sound waves from the microphone into numbers by sampling the signal at specific intervals, which are then converted into binary numbers (0s and 1s). The digital to analog converter, or DAC, that follows the ADC converts the binary values into sound for the person on the other side of the call to be able to perceive. This is why the signal is good – even if there’s noise, the DAC corrects errors by determining if something looks closer to a 0 or a 1.
But, there is a tradeoff. For example, in audio, having a higher sampling size means better quality, but all the numbers need to be transmitted quick enough for it to be continuous. One second of audio with a one second pause is not worth it, so it is important to find the balance between quality and efficiency.
The process of digitization as it applies to text is similar. Each character, including letters, numbers, and punctuation, is associated with a string of binary code. Computers use this binary code to produce text without any noise because it only needs to differentiate between a 0 or a 1.