Courts of appeals are higher-level courts that review decisions made by lower courts, such as trial courts. Their main role is to determine whether legal errors occurred during the trial that could have affected the outcome. These courts do not conduct new trials; instead, they examine the records of the case and listen to arguments from both sides. In the United States, each state has its own court of appeals, and there are also federal courts of appeals that handle cases from federal district courts. The decisions made by these courts can set important legal precedents that influence future cases.