According to Wikipedia:
"Quilling or paper filigree is an art form that involves the use of strips of paper that are rolled, shaped, and glued together to create decorative designs. The paper is wound around a quill to create a basic coil shape. The paper is then glued at the tip and these shaped coils are arranged to form flowers, leaves, and various ornamental patterns similar to ironwork."
These pictures are great examples of quilling as well.
image from homework blog
image from iron maiden
Quilling is also a beautiful option to add to wedding invitations. Check out this lovely invites and it how the quilling details really adds texture and sophistication.
image from all things paper blog
Here's a link to a how-to make quilled cards. Have fun!