Once the college/university receives the application & supporting documents, they will be reviewing the same to check your eligibility for the desired program. Once satisfied, the college/university will be issuing the admission offer letter. If the college/university is satisfied with the submitted documents/information they will provide an Unconditional Offer Letter. Else they will provide a Conditional Offer Letter and you will be required to fulfill the conditions mentioned in the offer letter to get the Unconditional Offer Letter. For filing a student visa, it is mandatory to have an Unconditional Offer Letter from college/university.