Unless the activities on your computer are restricted to pure textual output (plain text files), your computer is going to get filled with a lot of "stuff" - stuff that can overfill a PC's capacity too much for the computer to function well. The problem is that while upgrading a computer is always an option, technology advances so fast that newer products (such as memory chips, new drives, etc. Hold the can perfectly vertical and spray the fan being careful not to spray the dust off the fan onto other sensitive parts of the computer like circuit boards or inside the motor casing. Wipe up remaining dust with your anti-static rag and then reassemble the computer. One thing that you certainly don't want to use to remove computer dust is a vacuum cleaner. If you find that you can't type information into one of these, you can effectively resolve the issue with a technician by calling it an input box, rather than a "white rectangle," or "place to put in text." Button - buttons perform a command after a user clicks them with a mouse. Problems occur when the text of a button is grayed out or if it doesn't appear to sink into the screen when clicked. Apple's Macintosh computer was among the first of a couple systems to establish a user-to-hardware relationship through a user-friendly interface. Today, we have quite a few operating systems. Some of the more popular ones are Windows Vista, Mac OS X, ZETA, IBM, Unix, and Linux. But even still, operating systems have extended onto to non-computer devices such as game consoles, portable music players, and PDAs. Every computer can be broken down into four major components: CPU unit, monitor, keyboard, and mouse. For the novice, it's best to buy a computer that has all of these components included so that when it's taken home, assembling the computer is a simple matter of plugging things in where they belong. Sometimes, the data comes from an outside source like the Internet or the computer that the program runs on. The data that a program receives is called input and data that the program generates is called output. Other times, the data is unknown. If the program were working with a simple algebra equation like, "x + 5 = y," the variables "x" and "y" would be unknown pieces of data.