Linux is the most commonly-used operating system for web hosting in the world, and Linux servers are a popular choice for many websites and applications. It is the industry-standard operating system, and in fact, one of the most popular groups of applications used to back websites is commonly referred to as LAMP, which stands for Linux, Apache (a web server), MySQL (a database), and PHP.
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.