A DRM system used in many software products which uses a remote server to verify license validity, often limiting the number of computers on which the software may be installed. For questions about activating Windows, use [windows-activation].
Software activation is a DRM system used in many software products, where the software contacts a remote server to verify the validity of the license before allowing the software to run. Many implementations limit the number of computers to which the software may be installed, using information which identifies the computer or hardware configuration (such as hardware serial numbers). In most cases, licenses can be deactivated so that the software can be uninstalled and moved to another system.
For questions which involve activating Windows itself, rather than application software such as Microsoft Office, use windows-activation.