1.)
What is the Parallel Postulate?

Euclid's
Fifth Postulate, also known as the Parallel Postulate states as follows:

*"That,
if a straight line falling on two straight lines makes the interior
angles on the same side less than two right angles, the two straight
lines, if produced indefinitely, meet on that side on which are the
angles less than the two right angles."*

This
postulate is called the "parallel postulate" due to the fact
that it can be used to prove properties of parallel lines.

This
information was found on the following site:

http://aleph0.clarku.edu/~djoyce/java/elements/bookI/post5.html