There are literally millions. Well, okay, thousands. According to the Specialty Coffee Association of America, there are about 6500 species worldwide.
So let's make things a little more simple. There are two general varieties: Arabica and Robusta. Arabica are generally considered to be of a higher quality than Robustas. Arabica coffees make up about 70% of all coffees produced, and 100% of all the coffee we purchase.
Furthermore, the bulk of our coffees are known as "Strictly High Grown", indicating that they are grown at high elevations, This forces the coffee to grow more slowly, and creates a bean that is richer, deeper and more flavorful than most coffees.