Unicode

Unicode is the universal character set that gives a unique number, called a code point, to every character in almost every writing system in the world, including English, Tamil, Hindi, Chinese, mathematical symbols and emoji. Code points are written as U+ followed by a hexadecimal number, such as U+0041 for "A".

Unicode defines the characters; encodings decide how the code points are stored as bytes. UTF-8 is the most common encoding on the web: it uses one byte for ASCII characters and up to four bytes for others, so plain ASCII text is also valid UTF-8. UTF-16 and UTF-32 are other encodings.