Windows Server Core

Server Core is an exciting new installation option available in Windows Server 2008 that enables branch offices, data centers, and other networking environments to greatly reduce the total cost of ownership (TCO) involved with deploying and managing Windows servers. The Server Core option is a new minimal installation option available that excludes large parts of the graphical user interface(GUI).

A Server Core installation includes only a limited number of server roles compared with a Full installation of Windows Server 2008. It also supports only a limited subset of the features available on a Full installation of Windows Server 2008. 

Benefits of Server Core

• Greater stability: Because a Server Core installation has fewer running processes and services than a Full installation, the overall stability of Server Core is greater. 

• Simplified management: Because there are fewer things to manage on a Server Core installation, it's easier to configure and support a Server Core installation than a Full one—once you get the hang of it.

• Reduced maintenance:Because Server Core has fewer binaries than a Full installation, there's less to maintain. For example, fewer hot fixes and security updates need to be applied to a Server Core installation. 

• Reduced memory and disk requirements: A Server Core installation on x86 architecture, with no roles or optional components installed and running at idle, has a memory footprint of about 180 megabytes (MB), compared to about 310 MB for a similarly equipped Full installation of the same edition. Disk space needs differ even more—a base Server Core installation needs only about 1.6 gigabytes (GB) of disk space compared to 7.6 GB for an equivalent Full installation.

• Reduced attack surface: Because Server Core has fewer system services running on it than a Full installation does, there's less attack surface (that is, fewer possible vectors for malicious attacks on the server). This means that a Server Core installation is more secure than a similarly configured Full installation.

Read more : http://technet.microsoft.com/en-us/library/dd184075.aspx