If you were to write a book for youngsters about how to play baseball, or an adult-oriented romance novel, your “audience” would be easy to identify. In the first example, you’d be writing for an age group between 7 and 11; the readers would all be interested in baseball; and they’d be, let’s say, beginner-to-intermediate level of capability and sophistication in the sport. In the second example, you could Google the demographics for who buys