There are two types of nose piercings: the nostril, on the side, and the septum, through the center. Nostril piercings are very popular, perhaps second only to the ear as a site for body jewelry. Septum piercings are less common but still well known. In cultures outside the United States, these piercings can have very precise significance about social status. WIthin the United States, meanings are generally more personal.
The primary reason most people choose a nose ring is aesthetic -- they like the way it looks. They wish to adorn their body and make it more beautiful, and this is simply the spot they chose.
Body piercings, including the nose, are sometimes chosen as a way to express individuality and "customize the body," that is, to modify it in a personally chosen way.
It is still quite common for women in contemporary India, and women of South Asian descent living elsewhere, to get their nostrils pierced for cultural reasons. Although traditionally a nose stud rather than a ring is worn in this sort of piercing, a woman of South Asian descent who isn't following strict tradition but nonetheless wishes to display a connection with her culture may choose a ring instead.
Rite of Passage
Some piercees choose to mark events and transitions in their lives with body piercings. This can include a nostril or septum piercing. The nose is one place where the transition can be marked visibly, for the world to see.
Some body modification enthusiasts like to put a ring through their nose instead of on their finger for an engagement or wedding or to mark some other moment of romantic commitment. This can make for a unique bond between a couple -- plus, it's a great way to show off a diamond.
It may seem counterintuitive that nose rings are easy to hide, but it's true. Septum piercings in particular can be hidden by either flipping the jewelry upside-down so that it sits inside the nose, or by wearing a small, staple-like device called a septum retainer. So, if a person desires a visible but easily concealed piercing, a septum ring is an appealing choice.
Some people like septum piercings particularly because of the way they can make a face look fearsome. In fact, it is believed that many cultures such as those in New Guinea that incorporated this piercing into their tribal cultural practices did so for just this reason.
Sometimes a nose ring isn't just a statement of individuality, but also a statement of belonging. Many subcultures, such as goths and punks, are very body-piercing friendly, and getting a nose ring can help someone feel like he fits in with his friends. It's a sign of a shared aesthetic in just the same way that haircuts and clothing fashions can be.
This is a variation on the right of passage. After a long illness or traumatic injury, some people like to get a piercing as an act of spiritual healing. It's an attempt to "reclaim" the body from its trauma; for some, inflicting intentional, chosen pain and transforming it into something beautiful -- the jewelry adorning the body -- can be a very powerful statement.
To be frank, many people don't spend a lot of time thinking about the deep reasons behind their body-piercing desires. They get a nose piercing or other modification because they think it looks and feels good, period.