A letter of reference is a document that highlights an individual's skills and achievements and is intended to serve as a testimony of their character. It is a document that is frequently used when applying for a new job or pursuing further academic studies. Some words that can be used synonymously with "letter of reference" include "testimonial," "recommendation letter," "letter of recommendation," "referral letter," "testimonial letter," and "character reference." All these words are used to convey the same message and serve the same purpose, i.e., to provide a formal endorsement of an individual's qualifications and abilities.