When you spend in England enough time how to be part of the society you will begin to get a lot of greeting cards and you will realise about the importance of them.
In England you always will find a section in every supermarket, in every single store, you will also find some specialized stores fully selling greeting cards. You can find several categories such as Christmas, Thanksgiving, Birthday Cards, Friendship, Thank You, Love, Sorry, Get Well, Party Invitations, Anniversary, Congratulations... even you can find cards to say you are angry-upset or delicate matters such as religion, sex or Gay-Lesbian, you will always find the right card for the feeling you are looking for. At the beginning this was really strange for me, as well as a friend who was travelling around Spain told me he didn't understand why he hadn't found any card shop there.
To be honest when I was a child I remember sending-receiving Christmas cards between family, it was always nice to get some of them but nowadays are just an article in disuse, now everybody gets a lot of e-cards or emails with impersonal messages, we have lost the illusion to buy a card, an envelope and write a nice phrase.
At this point I think, why English people is still using this amazing way to communicate feelings but then they just write a few words ("happy birthday", "I am sorry", "thank you", "Merry ") ??? If you ask them, surely their answer would be:
If I have to write hundreds of cards, won't expect that I will be funny and original...