Two-dimensional shapes, also known as 2D shapes, are flat figures that have length and width but no depth. Common examples include circles, squares, triangles, and rectangles. These shapes can be classified based on their properties, such as the number of sides or angles they possess. In geometry, 2D shapes are often studied to understand their characteristics, such as perimeter and area. The perimeter is the total distance around the shape, while the area measures the space contained within it. Understanding these concepts is essential in various fields, including art, architecture, and engineering.