In law, an appeal is how legal cases are reviewed. An appeal is made to a higher court than the one that made the initial judgment. This is usually an appeals court. In turn, appeals court decisions may be appealed in a supreme court. The person pursuing an appeal is called an appellant.
When a lower court judgement is filed, the losing party (appellant) must file a notice of appeal. The appellant must give the appeals court legal reasons for reversing the decision of the lower court. Usually the legal argument includes legal precedents that relate to this case. The other party, called a respondent or appellee files a brief that counters the claims of the appellant. In turn, the appellant may counter the response of the appellee with a final brief. Then, if the appeals court agrees to hear the case each party argues their case before the court. The appeals court may sustain the original court ruling. They may also reverse the decision sending it back to the lower court. No new evidence is introduced in an appeals court.