Elastic cord is a soft, clear, stretchy cord used primarily for fun, inexpensive jewelry. It's especially useful for projects with children, since it doesn't require a clasp.

Because it's stretchy, the knots tend to loosen. You can use a dab of glue to seal them, or, for a more durable solution, use crimps to permanently hold the loose ends after knotting.

Elastic cord will eventually age due to use and exposure to chemicals found in perfumes, lotions, sunscreens, chlorinated pool water, etc. Occasionally check the color of the cord. When it starts to yellow it's time to restring your project on fresh cord.