When you arrive at the court, you are directed to a particular courtroom where a trial is scheduled to start. Some courts provide a brief orientation talk or video to help acquaint you with the system. All prospective jurors take an oath or affirm that they will answer truthfully questions posed to them by the judge and the attorneys during the process.
The purpose of this questioning is to find out if there is some reason why it might be difficult for a prospective juror to be fair and impartial in the case to be tried. As a prospective juror, you are introduced to the parties and the attorneys in the case and given a list of probable witnesses. If you have some relationship to one of these persons, it might be difficult for you to consider the case impartially, and you will likely be excused from jury service.
You are also told a little about the facts of the case so that the court can determine if any past experience or prejudice might make it hard for you to be fair. You also have an opportunity to tell the court about anything else that might impact your ability to sit as a juror.
Generally, each side in a case has the right to ask that a certain limited number of jurors be excused without giving a reason (called a “peremptory challenge”). Each side can also make an unlimited number of challenges “for cause” (for a good reason). When attorneys make these “challenges,” it is not their intent to personally attack potential jurors, but to ensure that they engage jurors who can evaluate the case as fairly as possible for their clients.