The lines which are not straight are curves
The curve which does not crosses itself is simple curve.

Simple Curves:
A simple curve is a curve that does not intersect itself. It consists of a single continuous path without any self-intersections or crossovers. In other words, a simple curve can be drawn without lifting the pen from the paper and without crossing over any part of the curve.

Closed Curves:
A closed curve is a curve that forms a closed loop. It starts and ends at the same point, creating a fully enclosed shape. A closed curve can be simple or not simple, depending on whether it intersects itself or not.

Not Simple Curves:
Not simple curves, also known as complex curves, are curves that intersect themselves. They have at least one point where the curve crosses over itself, creating multiple paths within the curve. These curves are more intricate and can have various shapes and patterns.

Curves That are Polygons:
A curve that is a polygon is a curve consisting of straight line segments connected end to end. It forms a closed shape with straight sides. Polygons can have any number of sides, from three (triangle) to many.

Curves That are Not Polygons:
Curves that are not polygons are curves that do not consist of straight line segments. They can be smooth and continuous, forming various shapes such as circles, ellipses, or spirals. These curves have curved sides and do not form closed polygons.

Simple Closed Curves:
A simple closed curve is a curve that is both simple and closed. It does not intersect itself and forms a closed loop. A simple closed curve can be drawn without lifting the pen from the paper, and it does not cross over any part of the curve. Examples of simple closed curves include circles, squares, and triangles.

In summary, simple curves are curves without self-intersections, closed curves form closed loops, not simple curves intersect themselves, curves that are polygons consist of straight line segments, curves that are not polygons have curved sides, and simple closed curves are both simple and closed, forming closed loops without any self-intersections.