Interviewers meet many candidates, so a follow-up email serves two purposes: 1). showing appreciation, and 2). reinforcing your qualifications. Send it within two days, highlighting key points from the interview to remind them why you're the right fit for the job.
Sample Appreciation Letter
Dear Mr. Eduard Santos:
It was a great pleasure to meet you yesterday in your office at Company XYZ. Thank you for your time and consideration in our interview, and I hope I met your expectations as a potential employee of XYZ with my past experiences along your line of work as an intern at ABC and a former vice president of UP ORG. Our shared interest in the field of green technology surely made it an interesting talk!
Once again, thank you for giving me the opportunity to be interviewed yesterday. I hope I could be a suitable candidate for the position, and I look forward to hearing from the company in the coming weeks once a decision has been made.
Yours sincerely,
Juan Karlos Dela Cruz