React Components are the building blocks of a React application. They are reusable pieces of code that define how a part of the user interface should look and behave. Each component can manage its own state and props, allowing for dynamic and interactive web applications. Components can be classified into two types: Class Components and Functional Components. Class components are more traditional and use ES6 class syntax, while functional components are simpler and often use hooks for state management. Both types can be combined to create complex user interfaces, making React a powerful tool for developers.