Character Encodings

Let us start by considering basic facts about binary data. Generally speaking, binary data consists of streams of bytes. These bytes have numerical values from 0 to 255, as composed by 8 bits (zeros or ones). The meaning of the bytes depends on the application.

Now, compare binary data with character data. At first, most English speakers think of ASCII as character data—an international standard for converting byte data (numbers from 0 to 255) to characters. However , ASCII only defines the meaning of the lower 128 values—the remaining 128 possible numbers (also known as high-bit characters) don’t correspond to a specific character. On some systems, these high-bit characters are used to represent locale-specific information. For example, a French system might use high-bit characters to represent French-specific information, whereas an English system might use the high-bit characters to represent special graphics (such as the trademark symbol).