# Lines

A line represents a curve in space and is not attached to any surface or solid. A line is a one-dimensional geometric entity.

The color of a line is determined by the component collector to which it belongs.

A line can be composed of one or more line types. Each line type in a line is referred to as a segment. The end point of each line segment is connected to the first point of the next segment. A joint is the common point between two line segments. Line segments are maintained as a single line entity, so operations performed on the line affect each segment of the line. In general, HyperWorks CFD automatically uses the appropriate number and type of line segments to represent the geometry.

- straight
- elliptical
- NURBS

Lines are different from surface edges and are sometimes handled differently for certain operations.