Understanding your core customer is a very important process. This requires you to do a lot of digging and thinking about certain factors such as their basic demographics such as age, sex, etc., as well as social and or political interests, their preferred occupation(s), socioeconomic status, and so much more. This process can and should take a lot of research to find out. You should essentially be able to describe everything about your core customer and understand them better than even your best friend! Your core customer is someone who is most likely to recommend, refer, and support your brand. Here's an example: