UI components are the building blocks of a user interface in software applications. They include elements like buttons, text fields, sliders, and dropdown menus that users interact with. Each component serves a specific purpose, helping users navigate and perform tasks within the application. These components are designed to be reusable and customizable, allowing developers to create consistent and efficient interfaces. Frameworks like React and Bootstrap provide pre-built UI components, making it easier for developers to design applications without starting from scratch. This enhances user experience by ensuring that interfaces are intuitive and visually appealing.