Coffee beans are actually taken from the seeds of the coffee plant. To get the flavour we know, the beans have to go through a roasting process. This is an essential part of the coffee making process, and it is actually the last step. The time it takes to roast the beans, and the temperature which they are roasted at will determine the flavour.
When coffee beans are roasted they split. The formula used for roasting the bean will determine how strong the flavour of the bean is. When a bean is roasted for longer 
the stronger the characteristic is. However, when a bean is roasted for longer, it loses some of the caffeine content, so stronger flavour does not mean more of a buzz.
While many choose to buy ready-roasted coffee beans, this is something which you can actually do yourself at home if you prefer. This means you are getting freshly roasted beans for the best flavour.
It is easy enough to do at home, and you can experiment with times and temperatures to get just the right flavour coffee for you. You can even try blending different types of beans for a truly unique taste.