This is only relevant for DOS, not Windows. Understanding ASCII (American Standard Code for Information Interchange) was one of my first breakthroughs many years ago. It is pronounced "aski" and is a standard for the relationship between a symbol and a number.
When you press a key on your keyboard and the screen shows a character, it is nice to think that the character is just sitting in the key, just waiting to be activated. But it is not that simple.
I am going to jump over the scancode, which is what is actually sent when you press a key. This code is sent to a "converter" that decides which ASCII value is linked to the scancode, and then this ASCII value is again "converted" to a character on your screen.
In computing, only two states are possible: on or off, 0 or 1, and nothing else; and this fills 1 bit. A computer can only move 1s and 0s around, nothing else! Eight of these 1s or 0s grouped together are called a byte, and the letters and symbols you use are each defined by a series of 1s and 0s assembled into an eight-partition electronic box. Each partition can contain either a one or a zero (binary system).
With eight partitions, each of which contains one of two (0 or 1) available values, there are 256 possible patterns (2 multiplied by itself eight times) for creating a number value. As zero is also a valid number, you will often hear of the set of values referred to as 0-255.
Fortunately, computer manufacturers are pretty much in agreement over which symbol or letter should be allocated to which of the 256 values in the ASCII system. Let's use the capital letter "A" as an example. At the DOS prompt, or in a DOS word processor, try holding the left-hand Alt key down while you key in two or three digits on the numeric keyboard, for instance 65.
Then, to make everything a bit more fun (though easier for programmers) when they created Windows, Microsoft introduced another standard called ANSI, which uses other character values.
Luckily, the normal letters and numbers are unaltered, but a text file stored as ASCII and one stored as ANSI are two different things. Text files saved by DOS programs are in ASCII format, while text files saved by Windows are in ANSI (by default, anyway). Write and other Windows word processors are able to save in either format and convert between the two.
These are some of the foundations of data communication. We humans have not really got any further in mimicking the brain and soul's development, but it is progressing. The only reason for the computer's wide use is its speed. Forget about "intelligent" computers, even though experts are trying to convince us it is possible with talk of neural networks and the like.