Roasting coffee is the process of taking the raw, green coffee seed, and making it into the coffee beans we buy. There are generally two methods of roasting coffee: slow and fast roasting.
Slow roasting is where a low heat is used to remove moisture from the raw bean and the temperature slowly rises until the first crack which is usually at around 210 degrees celsius. The bean is then finished by raising the temperature for the desired roast level.
Fast roasting is where high heat is applied first which sears the beans initially, then once the first crack happens, low heat is then applied as the beans are already very hot themselves.