If I have less than 15 users, how do I decide which version of Server is right for me?

Counting users is one way to do it, but the more relevant considerations will be your IT requirements and the level of IT skill within your organization. If you’re a small business with limited in-house skills, Windows Server 2012 Essentials is an appropriate option. It’s simple, affordable, and easy to manage, and has been tailored to address common small business IT scenarios. Windows Server 2012 Essentials is the ideal solution if you plan to expand your business capabilities through the cloud as it is designed to facilitate your connection to online services. On the other hand, if you have some level of in-house IT skills and want the ability to tailor server roles to their unique environments, then Windows Server Foundation is potentially better suited to your business.