No single element of the Macintosh interface is as recognizable or as famous as the Trash can, which appears at the end of the Dock. It is, of course, the inspiration for the Windows Recycle Bin.
You can discard almost any icon by dragging it onto the Trash icon (actually a wastebasket, not a trash can, but let’s not quibble). When the tip of your arrow cursor touches the Trash icon, the little wastebasket turns black. When you release the mouse, you’re well on your way to discarding whatever it was you dragged. As a convenience, Mac OS X even replaces the empty-wastebasket icon with a wastebasket-filled-with-crumpled-up-papers icon, to let you know there’s something in there.
Tip
Learn the keyboard alternative to dragging something
to the Trash: Highlight the icon, and then press 
-Delete. This technique is not only far faster
than dragging, but it also requires far less precision, especially
if you have a large screen. Mac OS X does all the Trash-targeting
for you.
File and folder icons sit in the Trash forever—or until you choose Finder→Empty Trash, whichever comes first.
If you haven’t yet emptied the Trash, you can open its window by clicking the wastebasket icon once. Now you can review its contents: icons that you’ve placed on the waiting list for extinction. If you change your mind, proceed thusly:
Use the Put Back command. This feature flings the trashed item back into whatever folder it came from, even if that was weeks ago—just as it does in Windows.
You’ll find the Put Back command wherever fine shortcut menus are sold. For example, it appears when you right-click the icon or click the icon and then open the
menu.Hit Undo. If dragging something to the Trash was the most recent thing you’ve done, you can press
-Z—the keyboard shortcut for the
Edit→Undo command. That keystroke not only removes it from the
Trash, but also returns it to the folder from which it came.
This trick works even if the Trash window isn’t open.Drag it manually. Of course, you can also drag any icon out of the Trash with the mouse, which gives you the option of putting it somewhere new (as opposed to back in the folder it started from).
If you’re confident that the items in the Trash window are worth deleting, use any of these three options:
The Mac asks you to confirm your decision. (Figure 3-7 shows this message.) When you click Empty Trash (or press Return), Mac OS X deletes those files from your hard drive.
Tip
If you’d rather not be interrupted for confirmation every time you empty the Trash, you can suppress this message permanently. To do that, choose Finder→Preferences, click Advanced, and then turn off “Show warning before emptying the Trash.”
Figure 3-7. Top: Your last warning. Mac OS X doesn’t tell you how many items are in the Trash or how much disk space they take up. Bottom: The Get Info window for a locked file. Locking a file in this way isn’t military-level security by any stretch—any passing evildoer can unlock the file in the same way. But it does trigger a warning when you try to put it into the Trash, providing at least one layer of protection against losing or deleting it.
When you empty the Trash as described above, each trashed icon sure looks like it’s disappeared. The truth is, though, the data in each file is still on the hard drive. Yes, the space occupied by the dearly departed is now marked with an internal “This space available” message, and in time, new files may overwrite that spot. But in the meantime, some future eBay buyer of your Mac—or, more imminently, a savvy family member or office mate—could use a program like Data Rescue or FileSalvage to resurrect those deleted files. (In more dire cases, when you’re desperate to get something back, companies like DriveSavers.com can use sophisticated clean-room techniques to recover crucial information—for several hundred dollars, of course.)
That notion doesn’t sit well with certain groups, like government agencies, international spies, and the paranoid. As far as they’re concerned, deleting a file should really, really delete it, irrevocably, irretrievably, and forever.
Mac OS X has a command, therefore, called Secure Empty Trash. When you choose this command from the Finder menu, the Mac doesn’t just obliterate the parking spaces around the dead file. It actually records new information over the old—random 0’s and 1’s. Pure static gibberish.
The process takes longer than the normal Empty Trash command, of course. But when it absolutely, positively has to be gone from this earth for good (and you’re absolutely, positively sure you’ll never need that file again), Secure Empty Trash is secure indeed.
By highlighting a file or folder, choosing File→Get Info, and
turning on the Locked checkbox, you protect that file or folder from
accidental deletion (see Figure 3-7 at bottom). A
little 
icon appears on the corner of the full-size
icon, also shown in Figure 3-7.
Locked files behave like this:
Dragging the file into another folder makes a copy; the original stays put.
Putting the icon into the Trash produces a warning message: “Item ‘Shopping List’ is locked. Do you want to move it to the Trash anyway?” If so, click Continue.
Once a locked file is in the Trash, you don’t get any more warnings. When you empty the Trash, that item gets erased right along with everything else.
You can unlock files easily enough. Press Option as you choose File→Show Inspector. Turn off the Locked checkbox in the resulting Info window. (Yes, you can lock or unlock a mass of files at once; read on.)