The speed of light in a vacuum, denoted as “c,” is a fundamental physical constant representing the speed at which light and all other electromagnetic radiation propagates through the vacuum. Its numerical value is approximately 2.998 × 108 meters per second (m/s), or 186,282 miles per second (mi/s). This astounding velocity has profound implications in various scientific fields, including optics, relativity theory, astronomy, and astrophysics, where it influences the behavior of light, affects time and space, and plays a crucial role in measuring cosmic distances.