Linked from
The 6 pages that link to UTF-8, each with the reason it gives.
UnicodeBroader topic: It is the most widely used encoding for storing and transmitting Unicode text.
ByteBroader topic: UTF-8 shows why a character may occupy different numbers of bytes.
ASCIIRelated: Its ASCII-compatible prefix preserves existing text and software conventions.
Ken ThompsonRelated: Thompson co-designed UTF-8 with Rob Pike for Plan 9.
Text fileBroader topic: It is the dominant encoding for text files on the web.