How can comparison operators be used with characters in C?

"16.1.2. Comparing Strings and Characters The comparison operators in Table 16.1 can also be used for single characters because of the nature of the ASCII text table (see Table 2.4). Each alphanumeric character, including the various symbols and whitespace characters, is associated with an integer 0–127. We can therefore write statements like ('A' < 'a') , which is true since uppercase letters are ordered before lowercase letters in the ASCII table ( 'A' is 65 and 'a' is 97 and so 65 < 97 is true ). Several more examples can be found in Table"