The char type's internal representation is an integer and that
integer is it's ASCII value. Since there are relatively few possible
characters (a total of 128), the characters were assigned the values
from 0 to 127. Integers in the range of 0 to 127 can be stored in
1 byte of space, so sizeof(char) is 1.
We really would like to think of characters as letters, digits,
punctuation marks, etc, and not as numbers.
Nevertheless, it is sometimes useful to use the fact that the
letter A is followed by the letter B, etc.