Although not a requirement, your U.S. host can write a letter. We've provided a sample invitation letter for a B-2 visitor visa.Clearly state the purpose of the applicant's intended visit to the United States, along with the proposed dates of their arrival and departure. There is no requirement for an invitation letter. If you want to send on send it to your parents who in turn may present it to the US consulate. What should the letter say? I am writing to extend my humble invitation to you to visit me in the United States. If you require a formal invitation letter for a VISA to travel to WCET2025 in Phoenix, Arizona, please fill out the WCET 2025 Invitation Letter Request Form. Request a Visa Letter.