Most people have about four "wisdom teeth". These are also known as "third molars", one in each quadrant. They are way in the back where there is usually not enough room. Often, but not always, they need to be removed because of limited space, angled eruption, impaction, or they just can't erupt properly. Sometimes there are no wisdom teeth at all; they just didn't form. There also may be one, two or three of them.
Every now and then there is a patient with extra wisdom teeth. Often these are called "fourth molars". Here is a panoramic x-ray showing the developing fourth molars. If there is not enough room for wisdom teeth (third molars), there for sure won't be enough room for any extras.