is a Japanese word meaning 'folding paper' that has been
adopted into English and many other languages. The
Japanese word origami and the English word paperfolding
mean exactly the same thing. Every time you fold a letter
to fit it inside an envelope or make a wedge of paper to
stop a table rocking or turn down the corner of a page to
mark your place in a book you are doing origami. You are
also doing origami if you fold paper to make toys or
novelties, models of animals, birds and flowers,
mathematical models, abstract sculptural forms or even if
you just scrunch a piece of waste paper into a ball to
throw at a friend.
Origami then is a process, folding, applied to a material, paper. It's as simple and straightforward as that.
Where things get a little more complicated is when you start to combine folding paper with folding other materials, like plastic or metal foils, which fold in entirely different ways, or folding paper with other processes like cutting. There is more information about this in the 'What are the rules of origami?' section of this FAQ