In geometry, parallel means two lines in two-dimensional Euclidean space that do not intersect; or two lines in the same plane that never meet and that maintain the same distance from each other at every point. In three-dimensional Euclidean space, these lines also do not intersect, maintaining a constant separation between points closest to each other on the two lines. In analytic geometry, parallel means those lines with the same slope, as well as other curves with the same slope for every *x* value. The symbol for parallel lines is . For example, *A* *B* means that line *A* is parallel to line *B*.