Unstructured Supplementary Service Data (USSD) is a technology unique to GSM. It is a capability built into the GSM standard for support of transmitting information over the signaling channels of the GSM network. USSD provides session-based communication, enabling a variety of applications. USSD's main strengths are interactivity and low cost. It is often used by banks to provide their clients with a quick interface for basic account actions, or by MNOs who are introducing advanced user features. It is commonly used in banking, mobile polling and education but has virtually limitless applications.