Installing a program generally means:

• Copying the program file to a new folder your hard disk, usually under C:\Program Files\.
• Copying other files that the program file uses to the same folder.
• Copying some files to other folders. (For example, Screenbook Maker copies some files to your My Documents folder so that you can store new Screenbooks there).
• Registering components that need to be registered. Certain files may need to have extra information stored in a special system file called the Registry.
• Adding entries to Start > Programs, and optionally the desktop.

Because of the last three entries on the above list, you can't install a program simply by copying files to the program folder. And you can't simply remove a program by deleting the program file and the program folder. You may have to remove many other things from other locations.