Start with a clear salutation addressing the consular officer. This letter should detail the purpose of their visit, the length of their stay, and how they will financially support themselves while they are here.If you require a letter of invitation for your visa application, please submit a request for a letter of invitation. PLEAS NOTE: Full payment and complete registration is required before an invitation letter will be provided. 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. The applicant will need to submit the invitation letter and your supporting documents the U.S. consulate with their application for the B-2 visa. Just go to the USA Immigration website and you will find out the answer to your question. The laws can differ from country to country. If you are in need of a letter confirming your participation in the MicroTAS 2014 Conference, please complete the Visa Letter Request Form.