In criminal matters, an appeal can be filed generally only by a convicted defendant due to the double jeopardy principle, but in tort, equity, or other civil matters either party to a previous case may file an appeal. In an appeals case, the party filing the appeal is usually styled the petitioner and the party being sued in the appeal is designated the respondent.
Depending on the exact structure of the local legal system, an appeals court can also be called by the name of appellate court, court of appeals, superior court, supreme court, or other name.