A court decision is the final ruling of a case, it decides who wins and loses. It also decides what each party gets to take away from the lawsuit. A court can issue many rulings along the way before reaching a judgment. Errors in earlier rulings can cause the court to reach the wrong conclusion, however, a judge will only make one judgment for the entire case.
At higher courts, a panel of judges hears and decides the case. The Justices who sit on the Supreme Court usually vote on each case after reading the briefs submitted by the parties to the case. The lead justice on the case will write the majority opinion, while other Justices may write concurring or dissenting opinions. The Justices who dissent from the majority opinion will explain the alternative reasons for their decision. The opinions are published together in a collection called the United States Reports and are prefaced by a syllabus prepared by the Reporter of Decisions.
Once the case is decided, the ruling becomes law. A court decision may have precedential value for other courts to follow, or it might be overruled by a later ruling of a higher authority.
In cases where the decision has national significance, the Supreme Court will often decide the case. However, the Justices will sometimes refuse to consider a case because they believe it is not of national importance or that the Court does not have jurisdiction over the case.