Let’s talk types of coffee. From a variety standpoint, there are basically only two main categories: Robusta and Arabica.
Arabica has a more delicate flavor and lower acidity than Robusta. It is grown in higher altitudes and is more costly to grow and more difficult to grow, so they have a lower yield that makes it cost more. Robusta has higher amounts of caffeine but can grow in hot, low altitudes, and with less moisture. Most commercial beans are this variety.
Coffee beans are green so they must be roasted. They range in roast from light brown to very dark brown and are broken into three roast levels: Light, Medium, and Dark.
Light roast is considered most delicate but also has higher acidity. You get more of the original coffee bean flavor. Medium roast have a chocolate color, less acidity than the lighter roast, and a toasty flavor. The Dark roast beans are roasted until they caramelize and oils come out of the bean. They may look oily. They have a strong flavor. Blends will combine two or more of these roasting levels.