https://en.wikipedia.org/wiki/UTF-8
In UTF-8 encoding, each Unicode character is assigned a specially encoded string of variable length. UTF-8 supports character strings up to a length of four bytes, to which all Unicode characters can be mapped.
UTF-8 is of central importance as a global character encoding on the Internet.
UTF-8 is congruent with ASCII in the first 128 characters (indices 0-127).