Sequin is a small element with a hole in it. It's used to create jewelry, as well as for sewing and customizing clothing and accessories.
The most common sequin is round, but is now available in a variety of shapes and materials.
These small components can be sewn, glued or hung.
The sequin generally differs from the charm in two ways: it's smaller than a charm, and it doesn't have a ring, but a hole.