Protocol: A protocol is a set of rules or guidelines for communication between two or more entities. For example, the Hypertext Transfer Protocol (HTTP) is a protocol used to communicate between web servers and web browsers.
Delegate: A delegate is an object in Objective-C that is used to pass data between two objects. For example, a delegate can be used to pass data from a view controller to a model object. The view controller can use the delegate object to pass data to the model object, and the model object can use the delegate object to pass data back to the view controller.