scanf() single character (Program 6.7)

[[I code:forFun]]

In the book, we are told that it is best to put a space before the %c in the scanf format string.  This will cause scanf to skip over any white space characters in the input.

My question is, what whitespace in the input are we talking about?
The program asks us to enter a character, we enter a character and press Return.  So, the only two things I can picture in the input are the character and the 'Return'.   I am not understanding exactly what whitespace is being skipped, and exactly where it is coming from.

All I know is my program acts goofy without the space (I combined examples 6.2 - 6.7 into one program, and it seems to be just right for re-creating the issue as mentioned in the book).

[reidnez]

The user could theoretically input a space or a return before the value.