U2F is an open authentication standard that enables internet users to securely access any number of online services with one single security key instantly and with no drivers or client software needed. FIDO2 is the latest generation of the U2F protocol.
U2F was created by Google and Yubico, and support from NXP, with the vision to take strong public key crypto to the mass market. Today, the technical specifications are hosted by the open-authentication industry consortium known as the FIDO Alliance. U2F has been successfully deployed by large scale services, including Facebook, Gmail, Dropbox, GitHub, Salesforce.com, the UK government, and many more.