- A virtual proxy is a placeholder for "expensive to create" objects. The real object is only created when a client first requests/accesses the object.

- A remote proxy provides a local representative for an object that resides in a different address space. This is what the "stub" code in RPC and CORBA provides.

- A protective proxy controls access to a sensitive master object. The "surrogate" object checks that the caller has the access permissions required prior to forwarding the request.

- A smart proxy interposes additional actions when an object is accessed. Typical uses include:
    o- Counting the number of references to the real object so that it can be freed automatically when there are no more references (aka smart pointer),
    o- Loading a persistent object into memory when it's first referenced,
    o- Checking that the real object is locked before it is accessed to ensure that no other object can change it.