hollow, horny barrel of a bird's feather, used as the principal writing instrument from the 6th century until the mid-19th century, when steel pen points were introduced. The strongest quills were obtained from living birds in their new growth period in the spring. Only the five outer wing feathers (follicles) were considered suitable for writing; the second and third were especially preferred. Quills from the left wing were favoured because the feathers curve outward and away from a right-handed writer.

Goose feathers were the principal source of quills; quills from the scarcer, more expensive swan were preferred; but for making fine lines, quills from crows were better than either. Quill pens made from feathers of the eagle, owl, hawk, and turkey have also been used.