React Hooks are a feature introduced in React.js version 16.8 that allow developers to use state and other React features without writing a class component. They provide a way to reuse stateful logic between components and simplify the code by removing the need for classes and lifecycle methods. Hooks are functions that let you "hook into" React features like state, context, and lifecycle methods from function components. Some of the commonly used hooks are: 1. useState: This hook allows you to add state to functional components. It returns an array with two elements: the current state value and a function to update that value. 2. useEffect: This hook is used to perform side effects in functional components, such as fetching data or subscribing to events. It takes a callback function as its first parameter, which will be executed after every render. 3. useContext: This hook allows you to access the value of a context directly within a functional component. It takes a context object created by React.createContext() as its argument. 4. useRef: This hook returns a mutable ref object whose .current property is initialized with the passed argument (initialValue). The returned object will persist for the full lifetime of the component. 5. useReducer: This hook is an alternative to useState for managing complex state logic in functional components. It takes a reducer function and an initial state as arguments, similar to Redux. 6. useMemo: This hook can be used for memoizing expensive calculations so they are only recomputed when their dependencies change. It takes a callback function and an array of dependencies as arguments. These are just some of the hooks available in React.js, and they allow developers to write more concise and reusable code compared to traditional class-based components. Hooks have gained widespread adoption due to their simplicity and flexibility in managing state and side effects within functional components.