Kuratowski's Theorem is a fundamental result in graph theory that characterizes planar graphs. It states that a finite graph is planar if and only if it does not contain a subgraph that is a subdivision of the complete graph K5 or the complete bipartite graph K3,3. In simpler terms, this means that if a graph can be drawn on a flat surface without any edges crossing, it must avoid certain complex structures. This theorem helps in understanding the limitations of graph drawing and is essential for various applications in computer science and topology.