The gravity model is a mathematical framework used to explain the flow of goods, services, and people between two locations based on their size and distance from each other. It is based on the principle that larger and closer locations have a stronger gravitational pull, resulting in a higher volume of interactions between them. This model is commonly used in economics, geography, and transportation planning to predict trade patterns, migration flows, and other forms of spatial interaction. It is a powerful tool for understanding the complex relationships between different regions and can provide valuable insights for decision-making and policy development.