A ray is a straight line that starts at a point called the endpoint and extends infinitely in one direction. It has only one end point while the other side continues without end. Rays are used in geometry to represent directions and are essential for understanding angles and shapes.

Lines and angles are basic concepts in geometry. A line extends infinitely in both directions while an angle is formed when two lines meet. Types of angles include acute right obtuse straight and reflex. Understanding lines and angles is essential for solving geometric problems and constructing various geometric shapes.