Web hosting comes in different shapes and sizes. Which flavor is best for you depends on  what you are trying to do or what your "application" is. The major categories are: Shared Web Hosting, Virtual Private Hosting and Dedicated Hosting.

Within those categories you find subcategories such as e-commerce hosting and rich media hosting.  At a basic level, the major category differences break down between cost and performance.  Higher cost usually means more experienced administrators, higher performance, better tools and more resources.  Higher performance often means increased maintenance on your part, though you can mitigate this by paying even more to have someone manage your hosting account. The main variables are raw resources and related costs such as disk space and bandwidth consumption, the more products in your catalog the more disk space is required and the more visitors you've got generating traffic, the more bandwidth your site will consume.