Windows Server is a server operating system that enables a computer to handle network roles such as print server, domain controller, web server, and file server. As a server operating system, it is also the platform for separately acquired server applications such as Exchange Server or SQL Server.
You can use this guide to find the Windows Server edition and licenses appropriate for your organization's needs.
Microsoft offers Windows Server through TechSoup in the Standard, Datacenter, and Essentials editions. The Standard and Datacenter editions have identical features, but they differ in the number of virtual instances of the server software you are allowed to run. Essentials shares many of the features of the other two versions, but not those appropriate only to medium-to-large enterprises. It replaces Microsoft's Small Business Server 2011 Essentials product.
- The Standard edition is designed for small-to-medium-sized organizations. Each Standard edition license allows you to run two instances of the server software in a virtual operating system on one server. Multiple Standard edition licenses can be combined to run additional virtual instances.
- The Datacenter edition is optimized for large-scale virtualization. Its license allows one server to run an unlimited number of Windows Server instances.
- The Essentials edition is designed for small organizations with up to 25 users and 50 devices. Its license allows only one instance of the server software to be run in the physical or virtual environment (Essentials edition licenses can't be combined). Client access licenses (CALs) aren't needed.
The Standard and Datacenter editions of Windows Server both use processor-based licensing, with each license allowing up to two physical processors. Multiple licenses can be obtained and applied to a single server to accommodate servers with more than two physical processors. The Essentials edition license also allows up to two physical processors, but licenses cannot be combined: two processors is the maximum the Essentials edition supports.
For each Standard Edition software license you assign, you may run one instance of the server software at any one time in the physical operating system environment (OSE). You may also run two instances in virtual OSEs on the licensed server.
However, if you run two instances in virtual OSEs, the instance in the physical OSE may be used only to run hardware virtualization software and to manage and service OSEs on the licensed server.
Datacenter Edition licenses include unlimited virtualization rights. You have the use rights to run an unlimited number of virtualized instances of Windows Server on the licensed server.
An Essentials Edition license allows you to run just one instance of the server software at any one time in either the physical or virtual OSE.
Client Access Licenses and External Connector Licenses
Windows Server Standard and Datacenter editions require a Windows Server user or device CAL for each user or device accessing or using the server software. No CALs are needed for the Essentials edition, which means the maximum of 25 users and 50 devices can't be exceeded.
Alternatively, an organization can use a Windows Server external connector license (ECL) for a large number of authenticated external Internet users. An external user is a person who is not an employee or someone to whom you provide hosted services using the server software. No CALs are needed for anonymous Internet users, such as unidentified users browsing the organization's public website.
Remote Desktop Services
If the server is running Remote Desktop Services, separate Remote Desktop Services CALs or ECLs are required to access the services. Remote Desktop Services allows the remote execution of applications from a wide range of devices over virtually any type of network connection. It was known as Terminal Services before the release of Windows Server 2008 R2.
Rights Management Services
If the server is running Rights Management Services (RMS), separate RMS CALs or ECLs are required to access the services. RMS is information-protection technology that works with RMS-enabled applications to help safeguard digital information from unauthorized use. RMS functionality is included in the Windows Server license.
How to Get CALs and ECLs
Microsoft offers the CALs and ECLs for Windows Server and for Remote Desktop Services through TechSoup. RMS licensing is not available through TechSoup at this time.
Server Application Licenses
Licenses for server applications — such as SQL Server or Exchange Server — that run on the Windows Server platform are separate. General licensing requirements for server applications offered through TechSoup can be found in the product descriptions. For details, see the Microsoft Product Use Rights documents.
Detailed Licensing Information
For detailed licensing information, see Windows Server 2012 Licensing & Pricing FAQ. (Pricing information does not apply to Microsoft products available through TechSoup.)
Complete licensing information can be found by clicking the Download the current PUR document link on the left side of the Microsoft Product Use Rights page. Select the English language link from the list.
If you have earlier versions of Windows Server or Small Business Server with active Software Assurance, you can upgrade to Windows Server 2012. See the Windows Server 2012 Licensing & Pricing FAQ for details.
For help upgrading, see the section "Upgrading previous retail versions of Windows Server to Windows Server 2012" in the Windows Server TechNet Library.
CALs, ECLs, and management licenses (MLs) work if they are for a version equal to or earlier than their server software. However, if you upgrade to Windows Server 2012, you will also need to use Software Assurance to upgrade the CALs.
CALs, ECLs, and MLs offered through TechSoup are always for the currently offered version. The Windows Server and Remote Desktop Services licenses, including those in the Core CAL suites, apply to Windows Server 2012 and earlier versions. Windows Remote Desktop Services and Windows Terminal Services CALs are interchangeable.
Windows Server Products Available Through TechSoup
Search for Windows Server donations available through TechSoup.