Finder

Finder was written by Bruce Horn and Steve Capps for the original Macintosh in January 1984 and was what the user saw once the machine had booted: a desktop, disk icons, folders that opened as windows and a trash can. The name referred to finding your documents, and the ideas came from Xerox Star by way of Lisa, with one crucial difference: Finder was an ordinary application the system launched, not part of the system. On a machine that ran one program at a time, that meant Finder quit when you opened MacWrite and relaunched when you left, a seam that MultiFinder papered over in 1987.

System 7 in 1991 added aliases, labels and drag-and-drop between applications. Mac OS X in 2001 rewrote it in Carbon with a browser-style window, a toolbar and the column view borrowed from NeXT's Workspace Manager; in 2009 it was rewritten once more in Cocoa. The spatial model, in which every folder remembers the position and size of its own window, was lost along the way, to the lasting grief of a small but vocal group of users.