A greeting card is an illustrated, folded card featuring an expression of friendship or other sentiment. Although greeting cards are usually given on special occasions such as birthdays, Christmas or other holidays, they are also sent to express thanks or other care. Greeting cards, usually packaged with an envelope, come in a variety of styles, are manufactured as well as hand-made by hundreds of companies big and small. These days, greeting cards with die-cuts or glued on decorations may cost up to five dollars each.
Hallmark Cards and American Greetings are the largest producers of greeting cards in the world. In the United Kingdom, it is estimated that one billion pounds are spent on greeting cards every year, with the average person sending 55 cards per year.
In the United States, many adults traditionally mail Christmas cards to their friends and relatives in December. Many service businesses also send cards to their customers in this season, usually with a universally acceptable non-religious message such as "happy holidays" or "seasons's greetings".

Types of greeting cards
The custom of sending greeting cards can be traced back to the ancient Chinese, who exchanged messages of good will to celebrate the New Year, and to the early Egyptians, who conveyed their greetings on papyrus scrolls.
By the early 1400s, handmade paper greeting cards were being exchanged in Europe. The Germans are known to have printed New Year's greetings from woodcuts as early as 1400, and handmade paper Valentines were being exchanged in various parts of Europe in the early to mid-1400s.
However, by the 1850s, the greeting card had been transformed from a relatively expensive, handmade and hand-delivered gift to a popular and affordable means of personal communication, due largely to advances in printing and mechanization.
This trend continued, followed by new trends like Christmas cards, the first of which appeared in published form in London in 1843 when Sir Henry Cole hired artist John Calcott Horsley to design a holiday card that he could send to his friends and acquaintances.
In the 1860s companies like Marcus Ward & Co, Goodall and Charles Bennett began mass producing greeting cards. They employed well known artisits such as Kate Greenaway and Walter Crane as illustrators and card designers.
Technical developments like color lithography in 1930 propelled the manufactured greeting card industry forward. Humorous greeting cards, known as studio cards, became popular in the late 1940s and 1950s.

History
Greeting cards derive from postcards which are single sided without the fold. Postcards appeared fairly early on in the history of the Postal Service as a cheaper way of sending messages, especially those of a tourist nature.