The greatest common divisor (GCD) has significant applications in number theory and practical scenarios like tiling. For a rectangle with integer dimensions, the largest square that can tile it perfectly has a side length equal to the GCD of its width and height. This principle ensures that tiles fit correctly without needing adjustments, which is crucial for aesthetic and functional purposes in flooring. While the GCD is a fundamental mathematical concept, its direct applications may not be extensive beyond basic tiling and number theory. Overall, the GCD serves as a foundational tool in various mathematical and real-life contexts.