As a cat owner, you'll know felines are extremely thorough when it comes to their grooming routine. They spend hours each day cleaning their faces and maintaining their coats. This also means they swallow a lot of hair, which can develop into hairballs or "fur balls".
Normally, most of the swallowed hair is expelled through the cat's digestive system in their stools. Hairballs commonly occur when hair accumulates in a cat's stomach or small intestine, forming a dense ball or mat which can't be passed. Often this ball is then vomited up.