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. Or if a program were to calculate a date "x" days from now, the variable "x" would be an unknown piece of data until we tell the program what "x" is. Most computer users don't know which files are safe to delete and which aren't. The worst thing anyone could do is snoop around crucial Window directories and haphazardly delete files that don't look familiar. Doing so could render important programs inoperable, corrupt the Windows operating system, and possibly prevent the computer from even starting. You can do this through Internet Explorer by typing in the address and password required to access the router (the address and password required to access the router will be in the router manual). Connected to the network, each computer can send files back and forth, open programs on a remote computer, play the sound files and videos located on another computer, and share a single Internet account to browse the web, download files, or chat with someone in an entirely different country. If you use an online service like AOL (America Online), you can use its internal Parental Control settings to block access to various chatrooms and websites. You could even block instant messaging and email from anyone who isn't a fellow AOL user. Other tools available online operate similar to the way that AOL's Parental Control settings work, however no collection of tools could replace the reinforcement of mom and dad. This is of course, assuming the kids are too young to whine about not having enough SDRAM or less than a 160GB hard drive. Today's "older" computers are perfectly capable of accommodating the needs of young PC users, and they're excellent machines for playing educational CDs, small multimedia files, or games downloaded from the Internet. It keeps track of where things exist on a computer's hard drive as well. But perhaps most importantly for the end-user, the operating system is responsible for translating commands issued with a keyboard and mouse into binary code (010110101 stuff) that can communicate with a set of speakers, a printer, a scanner, and more.