You could think of the sites that share your server as your roommates; there's really not that much separating you from them. Sure, you can close the bedroom door, but they can still cause nightmares for you in the kitchen and the bathroom. In web hosting terms, all the sites share a single server's resources, so huge traffic spike on Site A may impact the neighboring sites' performances. It's even possible that another site could take down the shared server altogether, if it crashed hard enough.
FatCow Web Hosting was founded in 1998 in with the simple mission of providing the most reliable, affordable and fun hosting service for personal and small business websites. Since that time, we have grown into one of the largest and most influential hosting services in the industry. Throughout our growth we have stayed true to our core values. Today we provide all of our customers with a safe, secure, Green hosting platform all backed by the best support around, the Moo Crew.
Many services offer a low "starting price," but require you to prepay for two or three years of service to get that price. After the promotional period, the renewal price for some services can be two, three, or even four times the initial promotional pricing. While the initial deal might be incredible, the cost of transferring your site (or paying the added fee) in a couple of years may be something to consider.