Angles made by parallel lines Parallel lines are straight lines which have the same direction and so never meet. Arrowheads show lines are parallel.

Parallel lines are lines that never cross each other - they keep the same distance apart from each other. When two lines intersect, the opposite (X) angles are equal. On parallel lines, alternate ...

If you have forgotten your basic geometry, parallel lines are represented by the little squares you see above, which signify 90-degree angles.