Two-factor authentication

Authentication mechanism requiring two or more of the following: something you know (e.g., password), something you have (e.g., token), something that identifies who you are (e.g., biometrics).

Source: The State and Local Election Cybersecurity Playbook, Defending Digital Democracy Project, Harvard Kennedy School Belfer Center for Science and International Affairs, https://www.belfercenter.org/sites/default/files/files/publication/StateLocalPlaybook%201.1.pdf