When I was 17, my father hired me to help him with his side hustle. He was writing software for a tech startup; he paid me to write the user manual. At the time, along with my schoolwork, I had two other jobs. My earnings covered movies and gas. The payout from the startup never came, but my father became skilled in a then-emerging technology—an Apple II home computer—that was useful in his day job.

In my corner of middle-class suburbia, side hustles were a fixture; my friends’ parents had them as well. One, a scientist, advised junior colleagues how to improve their grant proposals. Another, a hospital chaplain, officiated at weddings and funerals. Our teachers tutored after hours. So when the opportunity to write The Ultimate Side Hustle Book came along, I was eager to find out what, if anything had changed.

I learned that the side hustle has remained a consistent feature in Americans’ work lives. According to the U.S. Bureau of Labor Statistics, the percentage of adults holding multiple jobs is about the same today as in 1980, when I was in high school—around 5%. On the other hand, when people answer surveys about whether they earn money outside their regular work, way more report picking up extra cash than say they have more than one formal job.

Online commerce, social media and emerging gig economy platforms are broadening the opportunities people have to earn extra money. But (obviously) there’s more to the modern side hustle than driving for Uber or renting out spare rooms on Airbnb. I found side hustles to fit seemingly every interest, goal, set of skills, and life circumstance. Just about everyone I asked had a side hustle story.

You’ll find some of those stories in the book, with advice and tips for a successful side hustle. It’s designed to be practical. Whether you want to earn quick money, finance a hobby, get paid to develop new skills, capitalize on your experience, or start your own business, you’ll find an idea. I hope you’ll pick up a copy and let me know what you choose.