Identities are the *sets of claims made about a subject*. Subjects are typically people, applications, devices, or organisations, but the most common application of identity is to individuals. Identities are typically linked to information about the subject, including details that are important to the use of their identity. This information includes attributes, or information about the subject. Attributes can include a broad range on information, from name, age, location, or job title, to physical attributes like hair and eye colour or height. When a subject wants to use their identity, they need to use one of a number of common ways to assert or claim an identity: - **Usernames**, the most commonly used means of claiming an identity. It is important to remember that usernames are associated with an identity and are not an authentication factor themselves. - **Certificates**, which can be stored on a system or paired with a storage device or security token. - **Tokens**, a physical device that may generate a code, plug in via USB, or connect via Bluetooth or other means to present a certificate or other information. - **SSH keys**, which are cryptographic representations of identity that replace a username and password. - **Smartcards** use an embedded chip. Both contactless and physical chip reader–capable cards as well as hybrid cards are broadly deployed, and cryptographic smartcards often have the ability to generate key pairs on the card itself.