Editing Parallel (geometry) (section)

===Two lines in three-dimensional space===
Two lines in the same [[three-dimensional space]] that do not intersect need not be parallel. Only if they are in a common plane are they called parallel; otherwise they are called [[skew lines]].

Two distinct lines ''l'' and ''m'' in three-dimensional space are parallel [[if and only if]] the distance from a point ''P'' on line ''m'' to the nearest point on line  ''l'' is independent of the location of ''P'' on line ''m''. This never holds for skew lines.