A game loop is a fundamental structure in video game development that continuously runs to keep the game active. It typically consists of three main phases: processing input, updating game state, and rendering graphics. This loop allows the game to respond to player actions, update character positions, and display the current game scene in real-time. The game loop ensures that the game runs smoothly and consistently, regardless of the player's actions. By repeating these phases at a high frequency, it creates a seamless experience for players, making it essential for games across various platforms, including PCs, consoles, and mobile devices.