What is the difference between ASCII encoding and Unicode encoding?

Unicode is a popular solution to solve the problem of ASCII code 256 characters. As you know, the ASCII character set contains only 256 characters, expressed by numbers between 0 and 255. Including uppercase and lowercase letters, numbers, and a few special characters, such as punctuation marks and currency symbols. For most Latin languages, these characters are enough. However, many Asian and Eastern languages use more than 256 characters. Several thousand. In order to break through the limit on the number of ASCII characters, people try to use a simple method to write computer programs for languages with more than 256 characters. Unicode came into being. Unicode uses double bytes to represent a single character, so that the numeric code is mapped to a character set in multiple languages within a wider range.