A courtesy card is a small but powerful tool used in business to show appreciation and respect for customers, clients or colleagues. There are several synonyms for a courtesy card, including gratitude card, thank you card, appreciation card, acknowledgement card, and recognition card. A gratitude card expresses thanks for an act of kindness or assistance, acknowledgement card recognizes an achievement or accomplishment, while a recognition card rewards a job well done. Appreciation cards denote gratefulness for a person's effort, while thank you cards express gratitude for a favor or a service provided. Whichever term is used, a courtesy card conveys a positive message and shows that a person or business values their relationship with others.