Brag Sheets are documents where you list your achievements, strengths, leadership skills, professional experience, and other information that could be helpful to your recommender.
Resumes are documents where you list your contact information, experiences and activities, education, awards and achievements, and skills.
Letters of Recommendation are usually written by teachers, counselors, supervisors, or any other adult who knows a student in a professional capacity. They can be required for all kinds of applications, from job, to college, to internships, and more. Check out the AVHS Counseling website's guide on How to Request a Letter of Recommendation