Laces have been around for centuries for use as fastening devices, decorations, or both. Ancient Greeks and Romans used them to fasten their sandals.
Definition
Aglets are the metal or plastic sheaths at the ends of shoelaces and ribbons.
Function
Aglets keep shoelaces from unraveling, make them easier to tie, and make them easier to feed through the eyelet. They can also serve a decorative purpose.
Aiguillettes
A similar word is "aiguillette"--shoulder cords on military uniforms. Aiguillette is the French word for aglet.
Etymology
Aglet comes from the Latin work "acus," meaning "needle."
History
It's not known exactly who invented shoelaces, but Harvey Kennedy is credited with inventing them in 1790--but this has been disputed.