A balloon catheter is a medical device used to treat various conditions within the body, particularly in the cardiovascular system. It consists of a thin, flexible tube with a small balloon at its tip. When inserted into a blood vessel or other passage, the balloon can be inflated to open up narrowed or blocked areas, allowing for improved blood flow or drainage. These catheters are commonly used in procedures like angioplasty, where they help widen narrowed arteries. They can also be used in other medical applications, such as urethral dilation or stent placement, making them versatile tools in modern medicine.