It is believed that necklaces have been worn since the Paleolithic and Neolithic time periods, originally composed of shells, bones, and teeth. Though it isn't known what the original purpose of necklaces were then, today they are used for both fashionable ornamentation and religious practice.
In basic terms, all necklaces fit into the following categories: They are either sized long (20" or greater), medium (between 16" and 20"), or choker (16" or less). All necklaces are also either endless, meaning no opening, or clasped with either a lobster, springring, toggle, fishhook, foldover, magnetic, or ball clasp.
One of the most popular styles is the pendant necklace. This includes lockets, solitaires, and drops. Pendants can attach to any kind of chain with either a fixed bale or slide, or a single or double hanging bale. Some pendants even double as brooch pins. Similar to the pendant is the lariat, a style inspired by the lasso with a decorative drop that is threaded through a loop to keep the necklace fastened.
Another classic is the chain necklace. Chains are comprised of metal links that are connected in a particular pattern. Some chains include omega, cable, rope, popcorn, mesh, snake, curb, san marco, S-link, and byzantine. If the individual links are prominent enough, the necklace can be classified as a Link necklace.
For a bold statement look, try a multi-strand necklace. These necklaces are comprised of various connected strands, usually with beads. If the strands are twisted together, the necklace is known as a Torsade.
Other styles include station, where the necklace is broken up my sections of stones or beads; tennis, where the same stone follows consistently all the way through, unvarying from shape or size; and graduated, where stones or beads start at a certain size and progressively become larger towards the center.