An Ordinary Differential Equation (ODE) is a mathematical equation that relates a function to its derivatives. It describes how a quantity changes over time or space, often representing physical phenomena like motion, growth, or decay. ODEs can be classified into various types, such as linear or nonlinear, depending on the relationship between the function and its derivatives. Solving an ODE involves finding the function that satisfies the equation. Techniques for solving ODEs include methods like separation of variables, integrating factors, and numerical methods. ODEs are widely used in fields such as physics, engineering, and economics to model dynamic systems.