Always thank your interviewer(s) after the interview with a Thank You Letter or email. They will notice if you don't, and you'll be wasting the opportunity to refer to issues discussed in the interview, provide additional information, and restate your interest in the position.
How to Write a Thank You Letter
Follow up with a thank you letter no more than 48 hours after you meet. A nice, handwritten note will show interest and care, but thank you emails are also acceptable. Write to each individual that interviewed you if it was with more than one person. If you can't find someone's contact information, it's okay to ask another person from the interview to pass your message along to them; better that than to not include them at all.
As you draft your thank you letter think back to the conversation or look back at your notes and include specific examples from your discussion. Reminding the employer of specific details from the conversation shows your interest in the position, company, or industry, and your eagerness to learn. One or two details is enough; you don't need to recount the entire interview. Finally, be sure to proof read a thank you letter as thoroughly as if it were a formal cover letter.
For information on following up with a contact after a networking event or informational interview, visit our networking page.