An intrauterine device is one of several contraceptive methods that are available to women. IUDs have been around for a very long time, and we know a lot about the risks and benefits associated with their use.
Their are two main advantages of the IUD. The first is cost and convenience. After a one time cost of insertion, there are no further costs. They are also very convenient - you don't have to remember to take a pill, for example. Because if the inability to 'forget' they tend to be highly effective in preventing pregnancy, more so than pills for example (from forgetting doses).
The main disadvantages of the IUD are as follows. First, there is a very small risk of puncturing the uterus when they are inserted (about 1 in 1000 risk); this risk is reduced if the doctor
putting in the device has been properly trained. Another major disadvantage is that there is a certain rate of the IUD accidentally coming out, maybe 1% of the time, usually shortly after insertion, requiring for the device to be put back in.
Finally, there is a higher risk of pelvic inflammatory disease (PID) with an IUD. PID is caused by sexually transmitted infections, so an IUD is not always the best solution for a young woman with multiple sexual partners. This is something to discuss with your OB / GYN doctor, however, as many young women do very well with IUDs.