Key Management Service (KMS).
KMS uses a host computer to establish an activation service on your local company network. With a KMS host you can activate thousands of computers at the same time when they regularly connect to the company network. If you use a KMS host to activate Windows, you can use the same host to activate Office 2010.
Multiple Activation Key (MAK).
With MAK, each computer activates Office 2010 with the Microsoft hosted activation servers over the Internet or by phone. MAK is recommended when you have fewer than 50 computers to activate, and for computers that are not regularly connected to the company network.
Volume Activation 2.0 Technical Guidance – Downloads
Frequently Asked Questions About Volume License Keys
Fundamentals of Volume Activation
Multiple Activation Key (MAK) Activation
Key Management Service (KMS) Activation
Microsoft Office 2010 KMS Host License Pack