From The Art and Popular Culture Encyclopedia
A quill pen is a writing implement made from a flight feather (preferably a primary wing-feather) of a large bird. Quills were used for writing with ink before the invention of the dip pen, metal-nibbed pens, the fountain pen, and, eventually, the ballpoint pen. The hand-cut goose quill is rarely still used as a calligraphy tool, mainly because many papers are derived from wood pulp and wear down the quill very quickly, but it is still the tool of choice for a few select professionals and does provide a sharp stroke, and more flexibility than a steel pen. The hollow shaft of the feather acts as an ink reservoir and ink flows to the tip by capillary action.
The strongest quills come from the primary flight feathers discarded by birds during their annual moult. Generally the left wing is favored by the right-handed majority of writers because the feathers curve out to the right, away from the hand holding the pen, but because of the current scarcity of substantial quills this is usually overlooked as the curvature is not actually so pronounced as to cause any difficulty to the professional.
Goose feathers are most commonly used; scarcer, more expensive swan feathers are considered premium. Depending on availability and strength of the feather, as well as quality/characteristic of the line wanted by the writer, other feathers used for quill-pen making include feathers from the swan, goose, crow, eagle, owl, hawk, and turkey. The barbs are always stripped off partially or completely as they are an impractical distraction. The fancy, fully plumed quill is a hollywood invention and has no basis in reality. Most, if not all manuscript illustrations of scribes show a quill devoid of decorative barbs.