What are buyer persons and why are they important for your business

Can you very specifically define who are you customers are ?  what are their interests, typically what age they are , what kind of youtube videos they like, what kind of books they read and what kind of online communities they may be part of ? What are the typical pain areas that they have when it comes to managing or growing their business ? What kind of tools they typically use to manage their businesses ? Are there specific types of events or conferences they regularly attend ?   When you are able to answer many of these and similar questions and get more specific, the better you will understand your customer and what will come out will be a Buyer persona