Segment
A part of a line consisting of two endpoints and all points between them.
Ray
The part of a line consisting of one endpoint and all the points of the line on one side of the endpoint
Opposite Rays
Are two collinear rays with the same endpoint.
Parallel lines
Are coplanar lines that do not intersect.
Skew lines
Are noncoplanar; therefore, they are not parallel and do not intersect.
Parallel planes
Are planes that do not intersect.