When Were Gussets Invented?

The word "gusset" was first used in 13th century France to describe the armpit of a suit of armor. Medieval knights could have been stabbed in this area during jousting matches, but the gusset kept them out of harm's way.
Fast forward to today and gussets are used to add durability and mobility to a variety of products, from construction equipment to blue jeans. They are designed to provide additional support and eliminate stress.