A reference letter is a document written by an individual who knows you well, such as a former employer or teacher, and provides information about your character, skills, work ethic, or academic performance. It serves as a recommendation from this person to another party, such as a potential employer or educational institution, vouching for your qualifications and suitability for the position or program you are applying for. The content of the letter typically includes details about your job duties, accomplishments, strengths, and any other relevant information that can help the recipient make an informed decision about your application.