A letter of admission is a document used to prove that an applicant has been accepted and invited to attend a particular school or institution. The main purposes of admission letters are as follows: 1. Visa application: Admission letter is usually one of the necessary documents for visa application. When applicants apply for a student visa, they are required to provide a letter of enrolment as proof that they have been accepted by the school. 2. Apply for a student visa: Some countries require international students to apply for a student visa upon arrival. The Letter of admission is one of the documents required for a student visa and is used to prove that the student has been admitted and has a legitimate purpose to study. 3. Declaration of Entry: Upon arrival in the country of destination, Customs and Border Control may require international students to produce a letter of admission to prove that they have a legitimate reason for entry and can legally stay in the country.