Not only does it make clothing more comfortable (and is much easier to sew!), but it can also add a stylish touch, such as decorative ruching in both fashion and home decor.
Braided elastic is made by interlacing (or braiding!) strands of rubber or latex with polyester, nylon, or cotton fibres. It has horizontal ribbing and narrows when you stretch it.
Fold-over elastic (FOE) is a soft elastic with a groove in the centre that makes it fold in half easily. It can be folded over fabric edges, acting as binding and elastic in one.