Letters of Recommendation for Graduate School
Most programs ask for three letters, and for PhD programs, at least two should come from people who have seen your research or advanced coursework up close.
Ask early, at least four to six weeks before your first deadline. Give each recommender your CV, a draft of your statement, the list of programs with deadlines, and a short note on what you hope they can speak to.
A letter from a professor who supervised your research beats a letter from a famous name who barely knows you. For professional programs, a supervisor who watched your work counts for more than a family friend with a title.
Many portals send the request the moment you enter a recommender's email. Enter them early, and check a week before each deadline that every letter has arrived.