React.createContext() is a React API for creating context objects. It allows you to pass data through the component tree without having to pass props down manually at every level. It is mainly used when some data needs to be accessible by many components at different nesting levels.

For example, consider a React app that has a context of a user, which includes information such as the user's name, email, and age. This context can be passed down through the component tree, allowing any component to access the data without needing to pass props manually.