For each copy of Windows Server 2003 that you install, a license is required. This license gives you the legal right to install the operating system. However, for each client that will access shares or services on the server, a client access license (CAL) is required.

Windows Server 2003 supports two licensing modes: per server licensing and per seat licensing:

• Per Server

• Per Seat

With per server licensing, licenses are purchased for each server based on the maximum number of concurrent connections at any one time. For example, if you select per server with 10 CALs, 10 users can connect to the Windows server at any one time. This is usually the preferred licensing mode for networks with only one server.

Conversely, with per seat licensing, a license is purchased for each client. This is usually the preferred licensing mode if you have more than one server. If you are unsure, select per server licensing as there is a one-time conversion from per server to per seat, but not vice versa.