The OS X Finder is an amazing thing, letting you create folder within folder, duplicate files, find your documents, and generally get stuff done. More and more, the Finder features are being integrated across all apps and documents on your Mac.
Case in point is the ability to find the directory path of a document from the document’s title bar, as well as being able to (since Mountain Lion, anyway) rename your documents in the title bar as well. All of this is thanks to the proxy icon, which Apple defines as: “An icon in the title bar of a document window that users can manipulate as if they were manipulating the corresponding file-system object.”
Here’s how to use them on your Mac.