If you have a small collection of computers around the house (and a small collection of computer users), you can connect each one of those computers to one another and share data, software, and hardware including a single Internet connection. There are many creative uses for home networking, however it's an ideal situation when upgrading each computer to the same capability is financially out of the question. In the business world, open source is all about image and when consumers witness corporations contributing (instead of selling) to the buying public, they gain big favor in the eyes of their users (plus tremendous opportunities to sell other items). Inviting the public inside a product's development builds community and trust. In the past, the warning was to avoid opening files from people that you don't know. Today it's really not safe to open files from anyone (without scanning the files) because that's how viruses get spread - through files - even by mistake. So even though your co-worker may have emailed a funny video, it's no more safe to open than a video downloaded from a complete stranger. Sit files don't install software - they merely archive a collection of them into one, or they significantly reduce the size of a larger one. Decompressing Files Assuming that you have Winzip or StuffIt installed on your computer, you can access the files archived inside a .zip or .sit file by simply double-clicking the archive (a file ending in a . In short, a computer virus is a software program designed to destroy or steal data. It attacks computers via distribution - often unknowingly - through email attachments, software downloads, and even some types of advanced web scripting. Viruses that destroy data are known as Trojan horses, viruses that explode their attacks are called bombs, and viruses that duplicate themselves are called worms. Fortunately you have this article to guide you through some of the most common extensions that you'll run into. But before you can see file extensions, you need to turn them on. From Windows Explorer, click on the "Tools" menu, and select "File Options." Click the "View" tab and then uncheck the box next to "Hide file extensions for known file types.