Orbifolds are a mathematical concept that generalizes the idea of a manifold, which is a geometric space that locally resembles Euclidean space. In simple terms, an orbifold is a space that looks like a manifold but may have singular points or "cones" where the space is not smooth. These singular points break the symmetry of the space and introduce interesting geometric properties. Orbifolds are used in various areas of mathematics, including geometry, topology, and physics, to study spaces with singularities and to understand the underlying structure of more complex spaces. They are also important in string theory and other areas of theoretical physics.