A popular misconception is that cases are always appealed. A losing party often does not have an automatic right of appeal. There usually must be a legal basis for the appeal—an alleged material error in the trial—not just the fact that the losing party didn’t like the verdict.
In a civil case, either party may appeal to a higher court. In a criminal case, only the defendant has a right to an appeal in most states.
An appeal is not a retrial or a new trial of the case. The appeals courts do not usually consider new witnesses or new evidence. Appeals in either civil or criminal cases are usually based on arguments that there were errors in the trial’s procedure or errors in the judge's interpretation of the law.