Bonds are issued by bail bond companies, and usually cost about 10% of the face value.  When a bond is issued, the bonding company guarantees that the defendant will appear in court at a given time and place.  The government entity in whose court the defendant must appear, is protected by the bond.  If the accused skips bail, its usually the bail bond company that hires the bounty hunter to capture the accused, and thereby recover a portion of the lost money.