A formal debate is a highly structured argument usually conducted under firm time constraints. One group of individuals, usually referred to as the affirmative team proposes a specific proposition. A second group of individuals, the negative team argues against that proposition. Periods of cross examination are available.
Debates can become highly technical and arcane.
In high schools and colleges around the country, there are thousands of debating teams that debate a single proposition many times each year. During the course of a year, individual teams make the case for and against the same proposition. It is a good discipline to have to make a public argument that one does not necessarily agree with. It forces one to look honestly at the same issue from different perspectives. Unfortunately, very much like attorneys, in the heat of competition, debaters quickly begin to worry less about the truth of the debating topic and more about winning.