Two lines that are always the same distance apart and never touch. this is called your Parallel lines
Two lines that do not intersect and are not parallel. this is called your Skew lines
Parallel planes are found in shapes like cubes, which actually has three sets of parallel planes. this is called your Parallel planes
If a line segment intersects two straight lines forming two interior angles on the same side that sum to less than two right angles, then the two lines, if extended indefinitely, meet on that side on which the angles sum to less than two right angles. this is called your Parallel postulate
