Two Factor Auth (2FA): “Two-step verification, abbreviated to TSV (not equal to two step authentication TSA nor to Two-factor authentication, abbreviated to TFA) is a process involving two subsequent but dependent stages to check the identity of an entity trying to access services in a computer or in a network with just one factor or secret, whilst there is no proof obtained that the bearer of the unit is identical to the owner of the unit. This is the simplest case of a multi-factor authentication, which might involve only one of the three types of authentication factors (a knowledge factor, a possession factor, and an inherence factor) for both steps.”