I have a couple brief notes to add to Uberfetus's excellent writeup about the Trash on Mac OS.
The Trash on the original System 1.0 did not serve the "temporary storage" function; rather, it was automatically emptied on every reboot, and I believe whenever you launched an application (this was before the advent of multitasking on the Mac with MultiFinder.) I believe that the Trash ceased to automatically empty starting with System 7.
The name "Trash" is a special file name, and cannot be used for any other files or folders. Whenever you try to create or rename a file or folder "Trash", you get an error reading, The name "Trash" is reserved by the system software. Please use a different name.
When you choose "Empty Trash..." from the Special menu in the Finder, you get a dialog box reading, The Trash contains n items, which use x MB of disk space. Are you sure you want to remove these items permanently? You can bypass this message by holding the Option key down while selecting the "Empty Trash" command. The ellipsis will disappear in this case, as Macintosh Human Interface Guidlines state that an ellipsis should indicate that a request for user input (a dialog box) will follow selection of the command.