Rhinoplasty, better known as a nose correction, can be performed to improve the function (reconstructive surgery) or the appearance (cosmetic surgery) of the nose.
One of the most common reasons for non-cosmetic nose surgery is a deviated septum. The septum is the thin wall between the nostrils that extends back into the nasal cavity. It can be twisted resulting in a smaller nasal passage on one side or the other, or even on both. A deviated septum can also cause a nose to be crooked, if the deviation is from birth or early childhood. Not only can a deviated septum impede your ability to breathe through your nostrils, if it is severe enough it could contribute to sinus infections.
But a nose correction can also be performed to meet aesthetic goals. Perhaps you are simply not satisfied with the way your nose looks- in which case rhinoplasty is an option you might want to look into. It can for instance increase or reduce the overall size of the nose, narrow the span of the nostrils, remove a hump or alter the tip or the bridge of the nose.