An advisory opinion is an opinion given by a court that is neither binding nor precedent. Sometimes a legislature, governmental agency, executive officer or other entity will ask a court for an advisory opinion.
Before a genuine case or controversy is brought before a court and when no precedent exists, courts may offer an advisory opinion that does not serve as an official ruling.
Typically, courts are restricted to hearing lawsuits that involve a genuine case or controversy, but other branches of government sometimes need guidance from courts about how they might rule in a situation that has previously never come before the courts. When courts offer this guidance, they do so in an advisory opinion.
An advisory opinion differs from a binding opinion, which becomes precedent when it is published after a court makes a decision in a case.