An electronic payment service for transferring funds by wire. Originally, wire transfers required the sender to make a cash payment to a teller at a bank or telegraph office. The teller would send a request via telegraph that the payment be made to an individual at another bank or office. Nowadays, these transfers may be conducted through the Federal Reserve Wire Network or the Clearing House Interbank Payments System, among others. Wire transfers are guaranteed funds, meaning that the payment cannot be revoked by the sender after the transfer is made.