Bail in the US criminal justice system

What is bail in the US criminal justice system and what is its purpose?
What are the choices a judge/magistrate has when determining a defendant's pre-trial status?
Why was there a call for bail reform and what changes were enacted in states that reformed their bail systems?
Identify one issue that you think is a problem in the current bail system in the US and propose a program/law/policy that you think would address that isssue and explain why.