Section 1.5: Windows Server 2003 Licensing

The use of Windows Server 2003 requires two distinct types of licensing: a product license, i.e., the CD-key, which allows you to install the Windows Server 2003 operating system on a computer; and a Client Access License (CAL), which allows clients to connect to the Windows Server 2003 computer.

Windows Server 2003 provides three CAL modes: a per server mode, which sets the number of concurrent users or clients that can log on to a specific Windows Server 2003 computer; a per user mode, which permits an unlimited number of concurrent users to connect to the Windows Server 2003 computer, providing each has a CAL; and a per device mode, which permits an unlimited number of concurrent client computers, or devices, to connect to the Windows Server 2003 computer, providing that each device has a CAL.