For the sake of order, it can be added that the digital signal, with appropriate coding, can have more than two values, e.g. coding on 4 voltage ranges will allow to store 2 bits in one state (similar to SSD disks that record more and more information in one memory cell). The second issue is the way of modulating the signal in analog and digital transmission, they do not necessarily have to be voltage or current levels, such as phase / frequency keying, or continuous analog phase / frequency change.
In the article below you will find a short description and a comparison of both "languages" used in electronics.
Analog signal
For example, if you have an analog watch, it shows the time with hands that move on the dial. The position of the hand is a measure of time. How much the pointer travels across the dial directly depends on what time it is. If the hour hand advances two segments across the dial, it means twice as much time has elapsed as the one segment represents. It sounds obvious, but is much more subtle than it seems at first glance, because the movements of the hands above the dial are a way of representing the passing of time. Basically this movement is not the same as time, but it is a representation of it, it is an analogy of time. This is what the term "analog" means (and hence comes from).
Until the beginning of the 20th century, when computers began to dominate science and technology, virtually every measurement was analog. For example, if the current was measured, it was done with a moving coil meter with a pointer traveling over the dial. The farther the pointer travels across the dial, the higher the current flows in the circuit, again the pointer is just an analogy (representation) of current. Until recently, all types of measuring devices operated in a similar way, from speedometers and scales to sound level meters and seismographs.
But analog technology isn't just about measuring things with dials and gauges. When someone says something is analog, it simply means that it is not digitally processed - the work that the system does, or the information it communicates, does not require electronic processing of numbers. For example, the old style movie camera is sometimes called an analog camera. It is able to capture an image (light) on a piece of plastic foil coated with silver-based chemicals that react to this light. After developing such a film, it can be used to recreate the captured scene. Basically the captured image is an analog the scene recorded on it.
Digital technology is completely different from analog technology. Instead of storing words, images and sounds as representations of them on materials such as magnetic tape or plastic film, the information is first converted in some way into numbers which are then displayed or stored in electronic systems. Hence the name of the signal - digital .
Today, most devices in operation use digital technology instead of analog. Smartphones owned by most of us transmit and receive calls using the conversion of the user's voice into numbers, and then send them from one place to another (simplified - there are a number of other elements on the way, such as base stations etc.) in the form of waves radio.
Digital technology has many advantages over analog solutions. It is easier to store information digitally and often takes up less space. The collection of vinyl records with music albums takes up a lot of space - all this music, however, can often be placed, after compression (unfortunately most often lossy), as files on a single CD, not to mention DVD or BluRay.
Moreover, digital information is usually more secure. Conversations made from e.g. a mobile phone can be encrypted before transmission, which is much easier to do when the information is digitized from scratch. The encryption (or making it difficult to understand easily) of analog communication signals - e.g. the old kind of landline phones - is much more complex and in practice it is only implemented in extreme cases. It is easy to send and store digital information together, and to check whether it has not been damaged during transport or storage, we can detect a distortion even on a single bit of information.
Another advantage of digital signals is that their users can edit and reproduce digital information seamlessly. To edit photos, videos or music stored in digital format on a computer, you only need an appropriate program, often available in the form of freeware programs. Editing or even playing some analog formats is much more difficult.
What kind of data representation is better - analog or digital?
Just because digital technology has its advantages does not mean that it is always better than analog technology. An analog watch can be much more accurate than a cheap digital watch, especially if it uses a precise mechanism to measure the passage of time. Basically, the most expensive watches in the world are analog watches (usuallyare considered works of art), although the most accurate atomic clocks for communication use digital protocols (e.g. GPS or NTP standards).
But will information stored in digital form be as long-lasting as analog information? Museums are filled with paper documents, and those written on papyrus or clay. Some of them date back thousands of years. However, no one saved the first e-mail conversation or recorded the first cell phone conversation. If you open a book on the history of photography, you will find reproductions of the earliest photos, but you will not see any photos taken with the first digital camera.
While digital technology is likely to dominate the future, unless it has already been done, analog technology will always have a place in our world. Note that digital circuits, digital gates deep in their structure contain analog circuits, based on transistors, but we try to switch such circuits "digitally" - "binary" avoiding working in the "analog" - "continuous" range.
Source: https://www.electronicproducts.com/Education/...Analog_vs_digital_what_s_the_difference.aspx#
