Something you have-authentication is accomplished through something you know, something you have and/or something you are. one form of authentication requires possession of something (something you have) such as a key, a smart card, a disk, or some other device. whatever form it takes, the authenticating item should be difficult to duplicate and may require synchronization with systems other than the one to which you are requesting access. highly secure environments may require you to satisfy multiple authentication criteria to guarantee authenticity.something you know, would be a piece of data known only to you, such as a password. something you are, would be a physical characteristic of you, like your fingerprint.