From KVM

OVMF "is a project to enable UEFI support for Virtual Machines".

The earlier contents of this article have been replaced with the following link to the OVMF whitepaper:

The whitepaper covers everything this article used to cover, and the whitepaper is much more up-to-date and extensive. Please use the History link near the bottom if you'd like to see the previous (now stale) contents.