BAIL is the CASH money you pay to the BONDSMAN to get you out of jail. You do NOT get this money back, ever. It is usually around 10% of the actual BOND.
BOND is a piece of paper (a promissory note) that the BONDSMAN gives the court for the full amount set by the Judge.
If you appear for trial, the JUDGE dismisses the BOND (the BOND is released), and the BONDSMAN is not out any money at all, and has made a profit of the 10% of the BOND.
If you do not appear, the BONDSMAN then must pay the full amount of the BOND (make good on the note). This makes the BONDSMAN very mad, and he/she will pay HANDSOMELY for a SKIP TRACER (Bounty Hunter) to find you, because that’s an awfully large amount of money to come up with. So... they find you and retrieve you, dead or alive.
/johnny
That's when they let loose the hounds and sic Dog the Bounty Hunter on you. In this case his parents and grandmother posted the bond, so he's not going anywhere -- and the prosecution knew it and knows it.
So then if Zimmerman’s parents and grandmother posted their houses to cover the $150,000 Bond to the court, then who did Zimmerman pay his $15,000 Bail to???? His parents and grandmother???