Segment
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
two collinear rays with the same endpoint
Parallel lines
coplanar line that don’t intersect
Skew lines
Noncoplanar they are not parallel and do not intersect
Parallel planes
Planes that don’t intersect