To reiterate: if given a summons by the court, in person attendance is mandatory (applies to all 50 states). After voir dire, if either the lawyer or judge has selected you as the juror and being presented with evidence relevant to the case: what types of cases were you assigned whilst being a part of the jury?
Also, what happens if the individual fails to willingly show up (non-excusals) in court on the appointed date when they’ve been handed a summons in the US? For reference, in my country where Jury Duty also exists: the offense for failing to show up in person incurs the equivalent of an ~800 USD fine.
You find out about the case before jury selection. Voir dire probes for possible biases you might have about the case and the defendant so they have to tell you about the charges. The case I got released from recently was about a non-fatal knife attack.
The big fines and stuff are, I think, usually not imposed unless you get in their face about refusing. I missed a summons once and said oops, my bad. They said fine, we’ll send you another one.
I think I’ve gone 5 or so times and only made it to voir dire once. Maybe that says they send more summons than they really have to.