The main types of coffee beans are Arabica, Robusta, Liberica, and Excelsa. Arabica beans are known for their mild and complex flavors, while Robusta beans have a stronger, more bitter taste.

Coffee should be stored in an airtight container in a cool, dark place. Avoid storing coffee in the fridge or freezer, as moisture can affect its flavor. Use coffee within a few weeks of opening for the best taste.

Espresso is a concentrated form of coffee brewed by forcing hot water through finely-ground coffee beans under high pressure. Regular coffee is typically brewed using a drip coffee maker or pour-over method, which results in a lighter, less concentrated drink.

Common methods include drip coffee makers, French press, pour-over, espresso machines, AeroPress, and cold brew. Each method produces different flavors and strengths.

Bitter coffee can result from over-roasting the beans, over-extraction during brewing, or using water that's too hot. Adjusting the roast level, grind size, and brewing time can help reduce bitterness.

On average, an 8-ounce cup of coffee contains 80 to 100 milligrams of caffeine. The exact amount can vary based on factors like the type of coffee bean, the brewing method, and the serving size.