感谢信是向帮助、关心和支持过自己的集体(党政机关、企事业单位、社会团体等)或个人表示感谢的专业书信，有感谢和表扬双重意思。写感谢信既要表达出真切的谢意，又要起到表扬先进、弘扬正气的作用。它广泛应用于个人与个人之间个人与组织之间，组织与组织之间，用于向给予自己帮助、关心和支持的对方表示感谢。
英文感谢信(1)
Dear John,
I am writing to thank you for looking after me after that unfortunate accident the other day, when I was knocked off my bike by a taxi. If it had not been for your assistance in giving me first aid and taking me to a nearby hospital, I fear that the consequences might have been much more serious
英文感谢信(2)
Dear Mr. Nichole,
I am writing this letter to you to thank you for telling me such exciting news. It is really a great honor me to be admitted to your college. I will never forget your great kindness and help in the process of my application. My gratitude is beyond words. Thanks again!
Sincerely yours, Brown
英文感谢信(3)
Dear Sir,
I am writing to express my thanks for your kind staff whose work number card is 2938.
I came across him/her just when I was on the plane which was ready to take off.
I meant to switch/turn off my mobile phone as the flight attendant asked when I happened to find it missing.
It was not long before he/she helped me find it that was lying on the floor, slipping from my pocket.
Thanks again for his/her kindness, making me enjoy a fairly smooth trip despite such an incident.
Yours, John/Mary