Can you explain the properties and characteristics of triangles?

Triangles are geometric shapes with three sides and three angles. The properties of triangles include the sum of angles always being 180 degrees, the side lengths determining the type of triangle (such as equilateral, isosceles, or scalene), and the Pythagorean theorem for right triangles. Characteristics of triangles include their area, perimeter, and the relationships between their sides and angles.