What is the difference between Targets, Executables and Products in Xcode

In Xcode under Groups & Files开发者_开发知识库 panel, what is the difference between Targets, Executables and Products?

Target: Defines how to build products. A target organizes the files and instructions needed to build a product into a sequence of build actions that can be taken.

Product: The result of building a target. (MyAppName.app) The resulting bundle, in other words.

Executable: Defines the environment in which to run/debug the product. An executable environment defines the program that should be used to run the product with. In many cases, this will be the product itself, but doesn't have to be. In addition, the executable environment defines any command-line arguments and environment variables which should be used.

http://developer.apple.com/tools/xcode/xcodeprojects.html