When you open a program, the Mac reads its computer code, which lies on your hard drive’s surface, and feeds it quickly into RAM (memory). During this brief interval, the icon of the opening program jumps up and down eagerly in your Dock.
You don’t have to wait for the application to finish bouncing—you’re wasting perfectly good computing time. Just switch to another program and get back to work; the newly opened program keeps right on launching in the background. This means you, Photoshop and Final Cut nerds.
For decades, opening a program on the Mac presented exactly the same thing every time: a blank screen, or maybe a welcome screen. It was up to you to specify what document you then wanted to work on.
Now, though, whatever documents were open when you last quit that program magically reopen, ready for you to get back to work. Everything is exactly as it was, including your window and palette positions. Incredibly, any text that was highlighted when you last quit the program is still highlighted, and the insertion point is just where you left it.
This is all extremely handy if you tend to work on the same documents day after day; the auto-reopened document serves as a nice refresher on what you were in the middle of doing. You can skip fussing with the Open command, remembering what you were doing, rearranging the windows the way you like them, and so on.
Then again, maybe you can’t stand this feature.
Fortunately, it’s easy to turn it off, either globally, ...