A more thorough explanation:

The finality rule, also known as the final-judgment rule, is a principle in the legal system that states a party can only appeal from a district court's final decision that ends the litigation on the merits. This means that a party must raise all claims of error in a single appeal.

For example, if a person is involved in a lawsuit and the court makes a decision on one aspect of the case, but the case is not yet fully resolved, the person cannot appeal that decision until the entire case is concluded. Only then can the person appeal the final decision.

The finality rule is important because it helps to prevent multiple appeals and ensures that all issues are resolved in a single appeal. This saves time and resources for both the parties involved and the court system.