Aramid fibers are a type of nylon of which the molecular structure are comprised of linked benzene rings and amide bonds.

The U.S. Federal Trade Commission (FTC) distinguished these fibers from conventional aliphatic polyamide fibers, i.e. nylon fibers, in 1974, collectively referring to aromatic fibers as "Aramids." In 1977, the ISO similarly included this name in its listing of synthetic fibers.

As is described in this technical guide, aramid fibers differ greatly from conventional fibers (nylon) in both their properties and applications. Aramid fibers are broadly classified as either para-compounds in which the molecular skeleton is generally linear, or meta-compounds with a zigzag skeleton. Typical examples of these polyamide fibers are shown as below.