Classifying Lines

Lines can be in the same plane or in different planes
When two lines are drawn in the same plane, they will either cross at one point or they will not cross at all

Parallel lines are lines in the same plane that never intersect

When lines cross, we say that they intersect. When they intersect and make square angles, we call the lines perpendicular

If lines intersect at a point but are not perpendicular, then the lines are oblique

Skew lines are lines that lie in different planes. They are neither parallel nor intersecting