A more thorough explanation:

A Circuit Court is a type of court in the United States that hears appeals from federal district courts. There are twelve federal circuits that divide the country into different regions. For example, the Fifth Circuit includes the states of Texas, Louisiana, and Mississippi. Cases from the district courts of those states are appealed to the United States Court of Appeals for the Fifth Circuit.

Each circuit court has multiple judges, ranging from six to twenty-nine. Circuit court judges are appointed for life by the president and confirmed by the Senate.

Any case may be appealed to the circuit court once the district court has finalized a decision. Appeals to circuit courts are first heard by a panel, consisting of three circuit court judges. Parties file “briefs” to the court, arguing why the trial court’s decision should be “affirmed” or “reversed.” After the briefs are filed, the court will schedule “oral argument” in which the lawyers come before the court to make their arguments and answer the judges’ questions.

Though it is rare, the entire circuit court may consider certain appeals in a process called an “en banc hearing.” En banc opinions tend to carry more weight and are usually decided only after a panel has first heard the case.

For example, if a person is convicted of a crime in a federal district court and wants to appeal the decision, they can appeal to the circuit court for their region. The circuit court will then review the case and make a decision on whether to affirm or reverse the district court's decision.