Mutual authentication or two-way authentication (sometimes written as 2WAY authentication) refers to two parties authenticating each other at the same time. In technology terms, it refers to a client or user authenticating themselves to a server and that server authenticating itself to the user in such a way that both parties are assured of the others' identity. When describing online authentication processes, mutual authentication is often referred to as website-to-user authentication, or site-to-user authentication. Typically, this is done for a client process and a server process without user interaction.