This causes the computer's motor to work harder - and a harder working motor can raise the electric bill! Worst case scenario: the motor can overheat and stop working as well. No motor equals no computer. Keep your computer's fan clean by preventing the fan from getting dirty or dusty in the first place. Perhaps we could make an effort to educate the people who want put viruses into the public about ways to display dissatisfaction with a service or product that don't involve harming innocent parties. In doing so, we just might reduce the number of virus news stories and protect our own investments at the same time. 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. Certainly enticing buys, there are a few problems with buying software off the shelves. On the shelf, software - otherwise known as "commercial software" - can be expensive, and incompatible, and outdated when compared to what's available online. Fortunately, there's an alternative to commercial software and although it isn't new, it's one of the most under-exploited opportunities in the computer industry. Windows Media Player will open and run this kind of file. .scr - This extension indicates a screen saver file. .sit - This extension indicates a Macintosh archive StuffIt file. They will not open on a Windows system without a special utility. .ttf - This extension indicates a font especially designed for use on a Windows system. Assuming that a computer is set up to operate on voice command - sure! Voice command software allows users to tell a computer what to do and the computer responds by fulfilling the user's commands. Although it's pretty new and still under development, voice directed technology has already infiltrated consumer service related systems.