What is interface in composite?

In the context of the Composite design pattern, an interface defines a common contract that both composite objects (which can contain other objects) and leaf objects (which are the individual objects) must adhere to. This allows clients to interact with both types of objects uniformly, treating individual objects and compositions of objects in the same way. The interface typically includes methods for adding, removing, and accessing child components, enabling a hierarchical structure where clients can manipulate complex tree structures easily.