He two lines<span> will not </span>always<span> share all planes, though. They can </span>be coplanar<span> on the same horizontal plane, for example, but not </span>be<span> on the same vertical plane. ... Also, in a three-dimensional </span>space<span>, </span>parallel lines<span> are </span>coplanar<span>, but skew </span>lines, which do not intersect and are notparallel<span>, aren't.</span>