A postcard is a rectangular piece of thick paper or cardstock that is typically used for sending messages without an envelope. It often features a picture or design on one side, showcasing landmarks, landscapes, or artistic images. The other side is reserved for a message and the recipient's address. Postcards are popular for personal communication and as souvenirs from travel destinations. Postcards can be collected as a hobby, with enthusiasts often seeking out unique or vintage cards. They are also used in marketing and advertising, allowing businesses to reach customers with visually appealing messages. Many people enjoy sending postcards to share experiences with friends and family.