This story originally appeared on BusinessInsider.com.
Take notice, incoming college freshmen — the richest person in the world has some advice for what you should study.
In a Twitter thread on Monday, Microsoft cofounder Bill Gates said if he were to enter college now, he'd major in artificial intelligence, energy, or biosciences.
He called them all "promising fields where you can make a huge impact."
Experts in technology and economics generally agree that there will be profound changes in the next 20 years in the way companies use AI to automate their factories, construction sites, and retail locations.
And the US biotech market is growing at impressive rates, particularly as private firms race to develop smarter drugs and treatment options for antibiotic-resistant bacteria.
Gates' advice to pursue at least one of these three fields comes from personal experience. As co-chair of the Gates Foundation, he has seen firsthand how much progress the world has made in automating menial jobs, eradicating disease, and bringing alternative energy sources to its poorest regions.
Bright-eyed 18-year-olds should take notice, he says.
"You know more than I did when I was your age," he wrote in the Twitter thread. "You can start fighting inequity, whether down the street or around the world, sooner."