ASCII and Unicode

The American Standard Code for Information Interchange (ASCII) is a character encoding standard used to represent text in computers and other devices that use text.
ASCII uses 7 bits to represent each character, this makes it capable of representing 128 different characters including numbers, English letters, special characters and control codes.
Being devised in the USA, ASCII has a bias towards English language and does not support other alphabets, special symbols, and accents typically used in other languages.

The eighth bit in an ASCII character was originally used for a parity bit for error detection, but was later incorporated, resulting in the Extended ASCII.
Extended ASCII can represent 256 different characters doubling the original set.
Some characters in the extended set are control characters, while others represent lowercase and special characters, additional graphical symbols and foreign characters.

Unicode is a character encoding standard with the goal of replacing all existing character encoding schemes, providing a unique number for every character irrespective of platform, program, or language.
Unlike ASCII, Unicode supports over a million characters and can accommodate characters and symbols from all languages around the world.
Unicode and ASCII are compatible, the first 128 Unicode characters are identical to ASCII.

UTF-8, UTF-16, and UTF-32 are the three encoding schemes in Unicode that define how a character’s numerical value is represented.
UTF-8 is a variable-length encoding system that uses 8-bit bytes. It is backward compatible with ASCII and more byte efficient for ASCII characters.
UTF-16 is a variable-length encoding system, using either 16 or 32 bits, more efficient for languages with characters not represented in ASCII.
UTF-32 is a fixed-length, using 32 bits for each character, providing the ease of byte alignment but is less memory efficient.

ASCII and Unicode are the foundations of text processing in computer systems, including input, display and storage.
The invention of ASCII and its standardisation led to efficient and consistent data exchange and communication across different systems.
Unicode resolves the internationalization issue, allowing the representation and interchange of a vast array of world languages and symbols. This has greatly influenced global digital communication and the internet.