> Language types such as char, int, short, and long do not come with a guarantee of how many bytes they occupy in memory.

Char is actually guaranteed by C to occupy exactly 1 byte in memory. It’s just that a byte can have more than eight bits in C. “Byte” is simply the smallest unit of memory addressable by a pointer.

Further down the article acknowledges that “C requires char to have at least 8 bits (CHAR_BIT >= 8), not exactly 8” and mentions the Honeywell 6000 as an example of a C implementation with 9 bits (and 36-bit ints).

Historically in computing, the size of a byte was hardware-dependent and not standardized. The Wikipedia article on “byte” cites Knuth’s 1968 TAOCP where byte denotes a unit which “contains an unspecified amount of information […] capable of holding at least 64 distinct values […] at most 100 distinct values. On a binary computer a byte must therefore be composed of six bits”.