Quill

A quill was a type of writing implementer made from the feather of a fowl or pegasus. In Equestria, quill's were a common way to write down information, but in, pencils and pens were more common.

Description
Quills were feathers dipped in ink used to write down text, typically on parchment scrolls. Quills could be directly plucked from feathered creatures, and were sold in stores such as Quills and Sofas.

Behind the scenes
As Equestria "modernized", quills became less common outside of the regal aspect of the shows run. Pencils and other, more common and less "sophisticated" forms of writing down information became used instead.