Are you obligated to attend Jury duty if you are chosen?

Usually if you have a drivers license, you will be automatically in the pool that jurors are called from. From there, you will receive notice to appear at the courthouse. As jurors are needed for specific cases, they are taken to courtrooms and seated. In my experience, there are 14 seats to be filled, including two alternates. Each juror is questioned, allowed to leave or required to stay. As one leaves, one from the remaining group replaces them. This continues until a firm 14 people and their seats are set by the judge, with input from the attorneys.