Cobordism is a concept in topology, a branch of mathematics that studies the properties of space. It involves the idea of two manifolds being "cobordant" if they can be connected by a higher-dimensional manifold. Essentially, if you can imagine a surface that smoothly transitions between two shapes, those shapes are cobordant. In more technical terms, cobordism classes group manifolds that share similar boundaries. This leads to the study of cobordism groups, which classify manifolds based on their boundaries. The concept is closely related to other areas in topology, such as homotopy and homology, and has applications in algebraic topology.