Cross-examination is a legal process in which an attorney questions a witness called by another party, in order to challenge their testimony or credibility. It typically occurs during trials and hearings, where one side has the opportunity to question a witness who has already testified for the other side. The goal of cross-examination is to expose any inconsistencies, errors, or weaknesses in the witness's testimony, with the hope of undermining their credibility and persuading the fact finder (judge or jury) not to believe what they have said. It is a critical part of the adversarial system of justice, where both sides are given an opportunity to present their case and challenge each other's evidence.