Single Sign-On (SSO) is a property of logical access control of multiple related, yet independent, software systems. With this property, a user logs in with a single ID such as a smart card or token and password to gain access to a connected system or systems without using different usernames or passwords, or in some configurations seamlessly sign on at each system. This is typically accomplished using the Lightweight Directory Access Protocol (LDAP) and stored LDAP databases on (directory) servers. A simple version of single sign-on can be achieved over IP networks using cookies but only if the sites share a common DNS parent domain. On the back end, SSO is helpful for logging user activities as well as monitoring user accounts. SSO is a common procedure in enterprises, where a client accesses multiple resources connected to a local area network (LAN).