Taahuname, or Taahhütname, is a Turkish word that means contract, covenant or escrow. In regards to an official invitation letter, it means that a person hoping to visit the United States has been formally invited by a U.S. citizen to visit the country.
An official letter of invitation is a personal document. It does not need to sound official. The formatting for the letter is similar to any other type of personal communication. The sender and the recipient’s information, such as names and complete addresses, is included. The purpose of the visit is stated, as well as what locations are to be seen and how long the visitor plans to stay with the host, or if the visitor is scheduled to stay elsewhere. It states whether the host plans to cover the visitor's travel and personal expenses. Specifics are required in order to be accepted by authorities.