IT service companies sell a variety of services and products to corporations and individuals alike. So how do you know which ones you should buy and when? Here’s a short list of the top 10 most popular things with a brief description of each one. Computer Services: Computer services cover everything from server and network support, to software licensing, and even managed servers. IT service companies can also help organizations to manage their data. Computer Services is very similar to IT support, but covers a slightly different area.