Should I send a thank you email after a college interview, and what should it say?

Yes, you should send one. It is usually optional rather than required, but it is a good professional courtesy and can leave a positive impression.

Keep it short, specific, and genuine. A few sentences is enough.

A solid thank you email should include your appreciation for their time, one specific detail from the conversation, and a brief note that the interview increased your interest in the school if that is true. You do not need to restate your whole application or try to sound overly impressive.

Something like this works well:

Dear Ms. Chen,

Thank you for taking the time to speak with me yesterday about your experience at Brown. I especially enjoyed hearing your perspective on undergraduate research and the way students build close relationships with professors. Our conversation made me even more excited about the collaborative environment at Brown.

I appreciate your time and insight.

Best,
[Your Name]

Avoid making it too long, too formal, or overly flattering. Also do not use the email to add major updates unless they specifically invited you to send more information.