Postcards are also called postcards, and their English name is Postcard. They are a form of email used to promote and promote companies and individuals to share travel memories. A postcard is a small printed matter, generally rectangular in shape. The size of a Hong Kong postcard is usually 145mmx105mm. The postcard size must comply with the requirements of the postal department. The front of the postcard is often printed with colorful and rich background patterns, as well as clear and detailed images of famous tourist attractions or landmarks. The back is usually in envelope format, where stamps can be affixed, the recipient's address and the content of the email can be written. Personalized messages can be written on the back of the postcard. content, send a message to friends, family or loved ones, or share travel experiences and memories.