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A software design pattern organizing how software objects are created. A prototype pattern creates an object by asking an existing example to copy itself, letting a client choose a concrete configuration at runtime through an object interface.

The Prototype pattern is a creational pattern that creates new software objects by copying an existing configured object through a common cloning object interface. A client keeps or selects a prototype and requests a copy, without naming the concrete software class or repeating its construction recipe.

It is useful when the concrete type is selected at runtime, when many objects share a configuration, or when reconstructing an initialized object is expensive. For example, a drawing application can duplicate a configured graphical object through the same interface for many shape classes. The contract must specify what is copied: nested mutable state may require a deep copy, whereas a shallow copy would retain reference aliasing. A copy should preserve the intended configuration while allowing independent changes where promised.

The prototype pattern is a creational pattern: a client asks a configured object to clone itself through a common object interface, and concrete prototypes implement the cloning operation. The client can thereby create objects without naming their concrete classes at every creation site.

Use it when the required configuration or concrete type is chosen at runtime, or when reconstructing expensive initial state is less convenient than copying a prepared example. A deep copy may be needed for independently mutable nested data; merely duplicating outer fields can leave reference aliasing. The cloning contract determines what is copied and what may safely be shared.