When should I use an Outlet and property, say for a button?

I can never remember, when sho开发者_运维知识库uld I use an Outlet and property, say for a button?

Property is a part of Objective-C language (automatic/manual generating of getter and setter for object instances of a particular class), outlet is a part of Cocoa API interface bulding (connecting NIB elements and object instances of a particular class). Write it on your sticky note :)