UTF8ASCII

UTF8ASCII is an informal term used to describe the relationship between ASCII text and the UTF-8 encoding. It emphasizes that the ASCII subset of Unicode maps directly to identical byte values in UTF-8.

In UTF-8, code points from 0 to 127 are encoded as a single byte with the same value as ASCII, which means any ASCII string is also a valid UTF-8 string. Non-ASCII characters, such as accented letters or non-Latin scripts, are encoded using multi-byte sequences in UTF-8, but they are distinct from the ASCII range. UTF-8 preserves ASCII compatibility while expanding to encompass all of Unicode.

Practically, this compatibility supports data interchange and software development by ensuring that ASCII content remains unchanged when stored or transmitted as UTF-8. The term UTF8ASCII is not an official encoding name but a descriptive shorthand to indicate the ASCII-compatibility property of UTF-8.

Example: the text Hello maps to the bytes 0x48 0x65 0x6c 0x6c 0x6f in both ASCII and UTF-8, since these characters lie in the ASCII range. This property underpins common software behavior, where ASCII data is safely processed in systems that use UTF-8 as their default encoding.

See also ASCII, UTF-8, Unicode.