A shape is considered "convex" if, for any two points within the shape, the line segment connecting them lies entirely inside the shape. This means that a convex shape bulges outward, with no indentations or inward curves. Common examples of convex shapes include circles, squares, and triangles. In contrast, a shape is "concave" if it has at least one indentation, causing some line segments between points to fall outside the shape. Convexity is an important concept in various fields, including geometry, mathematics, and computer graphics, as it affects how shapes interact and are processed.