If you get arrested and charged with a crime, you will be required to post bail before the police will let you go. A judge sets bail to guarantee that when the defendant is released, he or she will appear when required. The more dangerous or more likely the person will flee, the higher the bail will be.
If you have an attorney, he or she can convince the judge to release you on your own recognizance, which means you're free to go without buying a bond or posting bail. Since you'd be charged with a crime, you would need an attorney anyway, so this is the first step.
If you do need to post bail, you can do so by just paying up front. When you return for your appearance, the court will give you the money back. In cases where the bail is so high that you need to get a bail bondsman to help, you do so by paying the bondsman around 10% of the total bail amount (while securing the rest with collateral such as a car or a house). When you return to court, the bondsman gets the all the bail money back and keeps your 10%.
