The term for a shape with three sides is a triangle. Triangles are fundamental geometric figures characterized by having three vertices and three edges or sides. They can be classified based on their side lengths into equilateral, isosceles, and scalene triangles, or by their angles into acute, right, and obtuse triangles. The study of triangles plays a crucial role in geometry and trigonometry, with applications in various fields like architecture, engineering, and computer graphics. The triangle's stability and strength make it a widely used shape in construction. Its simplicity and versatility highlight its importance in both theoretical and practical mathematics.