One of the most common styles of earring is the hoop earring. Basically, it's a circle of wire worn through a permanent piercing made in the lower earlobe. What differentiates the various types of hoop earrings is the mechanism for how they open and close.

Most ear piercings and earrings are very thin, approximately 20g or 18g wire (the bigger the number, the smaller the wire). With modern body piercing, older, tribal piercing styles have been revived in Western culture and sometimes you see poeple with very large gauge ear piercings, up to a few inches in diameter.

These earrings are some of the most simple and oldest styles of jewelry. A single wire forms the circular earring, with a tiny loop formed at one end and the free end being slightly bent to make a hook. The hooked end passes through the piercing, and catches on the looped end.

This style can be made using a round wire or a ready-made earring wire that has the loop end already fashioned.

These earrings are often thicker than the ear piercings, with a thin wire for passing through the ear. One end of the ear wire is hinged and the other catches on or fits into the other thick end of the earring. Most often there is a slight hump to the ear wire which allows the lower portion of the earring to dangle more freely.

A lot of fashion earrings are designed like this style and they can support a lot of weight fairly securely.  You can lose this type of earring if it snags on something, as the sideways motion can easily open the hinged wire.

Some earring wearers find that over time their ear piercings become elongated. This means that what were once small holes become more like long slits, with the amount of tissue between the bottom of the ear piercing and the edge of the ear lobe getting very thin.

The most common cause for this is genetics. What predisposes some people to thinner ear tissue that changes more over time isn't something that can really be addressed. See what the ear piercings of your mom and grandmother look like if you are wondering if you might have this genetic tendency.

The second most common cause of elongated ear piercings is something that can be monitored and that's the wearing of heavy earrings. The weight of an earring adds stress to ear wires and over decades, these thin wires can facilitate the stretching of the piercing downwards. Wearing heavy earrings for long periods of time or wearing them frequently is not recommended.  Large-size earrings (aka dangles or "chandeliers") that flap with movement or can get snagged easily can also contribute to ear piercing elongation.

Due to the nature of ear tissue, the only cure for this is earlobe cosmetic surgery.   Any tears or closures require plastic surgery and suturing to make the ear tissue grow together again.  And afterwards, the person still has to be careful about earring weight or the same problem will just occur again.

This style of jewelry is a lot like the wire loop, with a small bead taking the place of the looped end. The free end of the wire goes through the piercing and into the bead, hiding the actual opening mechanism and making the jewelry harder to lose or snag.

To change this type of hoop, the ring must be bent or deformed somewhat so you most often only see it in earrings or smaller gauge body jewelry. It's best to move the ends horizontal to each other to open the ring as this deforms the circular shape less and helps avoid breaking by metal fatigue.

With this type of hoop, the ring comes nearly all the way around to make a circle, missing just a small area. A bead, with two drilled depressions on each side of it, is pinched between the two wire ends (captured) and thus held in place. This style is available from the very small (20g) up to size 0 or larger.

Most often you see this type of jewelry worn in non-ear piercings, although they can be nice for small, upper cartilage piercings or any earring where you want to wear something very long-term and never change or take it out.