Writing a thank you letter after an interview is both polite and extremely important. Be sure to write a thank you note to anyone who interviewed or helped you during the application process. If you were interviewed by a panel, you can send one to the head of the panel.
Use the letter to express your appreciation for the interviewer taking time to meet with you and to re-emphasize your particular interest in the position. If needed, use the letter as an opportunity to clarify something you said in the interview or add something you forgot to say.
Your letter can be a few lines or a few paragraphs and may be typed or handwritten, as long as it is professional. Include the date of your interview and the position. Send your thank-you letter within 24 hours of the interview.