Unicode: UTF-8 Encoding

What is UTF-8

UTF-8 stand for Unicode Transformation Format, 8-bit.

〔see Unicode: Character Set, Encoding, UTF-8, Codepoint〕

UTF-8 is compatible with ASCII encoding. Each ASCII Character has the same encoding as UTF-8. This means, their byte sequence is the same, for any file encoded in ASCII or UTF-8. (excluding the case if the file began with a Byte Order Mark.)

UTF-8 is published in 1993. 〔see Unicode UTF8 History, by Rob Pike〕

UTF-8 is the most popular encoding, used by 98% of all web pages in the world as of 2022. 〔see How Popular is Unicode UTF-8〕

UTF-8 Encoding Scheme

UTF-8 is a variable width character encoding scheme. Each Codepoint of unicode is encoded to 1 to 4 Bytes.

in this scheme:

• if the byte begins with 0, it means the character is single byte, else multi.
• if the byte begins with 1, the count of leading 1 indicates how many bytes for the character.
• A byte is the starting of a character, if it does not begin with bits 10.
• you can find next/previous starting byte by searching for bytes that does not begin with bits 10.