a card with a picture on the front and a message inside that you send to somebody on a particular occasion such as their birthday Culturegreetings cardsSpecialist greetings card shops, newsagents and department stores sell millions of cards every year to help people celebrate important events in the lives of their friends and family. Most people send birthday cards. They also send cards to celebrate engagements (= agreements that two people will marry), weddings, births, moving to a new house and retirement from work, to wish somebody good luck, or to express sympathy when somebody has died. In addition, there are cards for Christmas and Easter, and other religious festivals.Most greetings cards are folded and have a picture on the front and a verse or message inside. There are also many cards that are blank (= without printed words) inside so that people can write their own message. Other cards say things like ‘just because I was thinking about you’, and are for people to send when there is no special occasion. There are also many postcards printed with simple pictures and messages such as ‘Miss you’ or ‘Write to me’. Some cards show famous paintings, others have country scenes, flowers, animals, etc. on them. Children's birthday cards often have a number for the child's age, and sometimes a badge (AmE button). Many cards for adults have cartoons or rude jokes about getting old, or humour with a strong sexual content.The most popular time to send cards is at Christmas. Christmas cards often have pictures of Santa Claus, reindeer (= a type of deer), robins (= small birds) and snow on them, as well as scenes from the story of Christ's birth. Many families send over 100 Christmas cards each year. People send cards to neighbours or people they work with, as well as to friends they see less often. Sending a Christmas card is a way of keeping in touch with friends and family members who live far away. Many people like to send charity cards, cards sold in aid of a charity, because they want to do some good for others at Christmas time. Business companies send cards to their main customers, and some have cards specially printed.Some special days are thought to have been invented by greetings card manufacturers in order to increase their profits, e.g. Father's Day, when children are expected to send a card to their father, and Grandparents' Day. Mother's Day is a much older festival which has its origins in the Christian Church. Another important date is St Valentine's Day, when people send cards to the person they love, sometimes without signing them, or signing them with phrases like ‘from a secret admirer’. In the US, children give small Valentine's Day cards to everyone in their school class.