Origami (literally meaning "folding paper") is the art of paper folding. The goal of this art is to create a given result using geometric folds and crease patterns.
Origami only uses a small number of different folds, but they can be combined in a variety of ways to make intricate designs. In general, these designs begin with a square sheet of paper, whose sides may be different colors, and usually proceed without cutting or fastening the paper. Contrary to most popular belief, traditional Japanese origami, which has been practiced since the Edo era (1603-1867), has often been less strict about these conventions, sometimes cutting the paper during the creation of the design (Kirigami) or starting with a rectangular, circular, triangular or other non-square sheets of paper.
Although almost any laminar material can be used for folding, the choice of material used greatly affects the folding and final look of the model.
Normal copy paper with weights of 70–90 g/m² (19-24lb)) can be used for simple folds, such as the crane and waterbomb. Heavier weight papers of 100 g/m² (approx. 25lb) or more can be wet-folded. This technique allows for a more rounded sculpting of the model, which becomes rigid and sturdy when it is dry.
Special origami paper, often also referred to as "kami" (Japanese for paper), is sold in prepackaged squares of various sizes ranging from 2.5 cm to 25 cm or more. It is commonly colored on one side and white on the other; however, dual coloured and patterned versions exist and can be used effectively for color-changed models. Origami paper weighs slightly less than copy paper, making it suitable for a wider range of models.