Blow are simple explanation on non-breakable space and trailing space.
[non-breakable space]
a,It's hard to type non-breakable space when you are typing.
b,It's invisible character.
c,It's 0xa0(hex),160(digit), in some encoding systems.
d,reference: http://en.wikipedia.org/wiki/Non-breaking_space
[trailing space]
a,It's just like:
abc[][][][end of line] #three trailing space represent as []
b,the whitespace between last character and end of line.
Notes:
Brushing up on whitespace in computer science.