This is Euclid's fifth postulate, also known as the Parallel Postulate.
It is quite possible to construct consistent systems of geometry where this postulate is negated - either many parallel lines or none.
A quadrilateral with only one pair of parallel lines is called a trapezoid.
A trapezoid has exactly one pair of parallel lines
Parallel lines don't intersect, no matter how many of them there are.
A trapezoid
Any line that is not parallel to the given lines. The transversal that contains the shortest distance between the two parallel lines, is perpendicular to them.
Skew lines are not parallel. Parallel lines are across from each other in some way and are exactly parallel.
A cube has exactly 6 parallel lines.
A cube has exactly 6 parallel lines.
A trapezium is a quadrilateral with two parallel lines.
A trapezoid is a quadrilateral with exactly two parallel sides.
A quadrilateral with only one pair of parallel lines is called a trapezoid.
A trapezoid has exactly one pair of parallel lines
Parallel lines don't intersect, no matter how many of them there are.
A cube has exactly 6 parallel lines.
It means when two lines meet. Parallel lines never meet; they stay exactly the same distance apart.
Parallel lines lying in a plane do not intersect each other. They share exactly zero points in common.
It is a trapezoid