I have had several summonses. Once I was raffled into the queue for the court rooms, though the jury was selected before my 'squad' was seated into the jury box (where you are interviewed by the lawyers contesting the case).

The other times, I've always shown up but never got past the raffle stage; and a few times there were too few cases for the number of summons that were sent out, so I didn't go in at all.

In most areas the summons have a phone number in addition to your unique summons ID. You call a day or two in advance and either a receptionist or a recorded "loop" will read off the blocks of numbers that are being called-in. If you are 29-057, you listen through the list and wait for "Summonses 28-030 through 28-100 please report to X, Summonses 29-001 through 29-040 report to Y, etc; all summons numbers in these sets need to report Monday at 7am blah blah blah. If your number falls outside the listed range, you do not need to report.".

Most of the time I've fallen outside the summoned numbers, but I've reported several times and only once been moved beyond that stage, as I mentioned. It varies a bit by court, but usually they call about five times as many summons as there are seats needed for the docket that day/week/month. If there are twenty cases, and the normal juror count is 12 per case, they will call in 240 times 5 or about 1,100 people. Some areas may only call in 3x, some may do higher multipliers. Anyway.

Once you are signed in, you sit in a holding area and a court agent will do a raffle-type thing for groups of 25-40 people at a time and escort you to a courtroom that has the judge, the lawyers, the bailiff, sometimes the complainant and/or the defendant (this depends). The lawyers for both parties get to interview prospective jurors, usually about topics relevant to the case at hand. The normal number is 12 jurors, and this is usually met from the pool of 25-40 though sometimes the selection process can go through dozens or hundreds of people.

Once the lawyers all agree on 13 (includes an alternate), those who were either not interviewed or who were not selected are escorted back to the holding room, and you can be called a second or even third time in the raffle process for possible selection.

In the case I was raffled into, the topic was financial contracts that someone was accused of breaking. The questions from the lawyers were things like: do you have debts, and what kind? Have you ever faced collections (eg. wage garnishment)? Have you ever owned or managed a business or handled accounts for a business that required you to draft or manage contracts? Are you currently (or have you ever) been signed to a contract that involved a financial transaction, such as a car loan? They did not ask about your feelings on immigration enforcement, for example, and did not ask about whether you ever smoked marijuana, or other issues that might be relevant to other court cases (but not to the case being contested that day/week).

The lawyers for both parties take notes and eventually one team will indicate they have enough acceptable candidates, the judge will ask if the other party has enough acceptable candidates. Once both say they've counted at least 13, the lawyers confer and see if they have the same names/numbers or not. If they agree on 13, the rest of the potentials (and any rejected candidates) are taken back to the holding room as I described. If the parties agree on 10, those ten are sequestered and the process continues until another 3 are agreed on.

Anyway. Most of the time if I go in, I just stay in the holding room, and the one time I was taken to a court room I got to listen to the interview process but both lawyers agreed on 13 before I was interviewed so I was sent back and didn't get raffled into any of the other cases that were making selections that day.