Facebook's Mark Zuckerberg shares his best advice for aspiring entrepreneurs

When Mark Zuckerberg took Facebook (FB) public in 2012, the IPO raised $16 billion, making it one of the largest IPOs of all time.

It's safe to say the Facebook co-founder and CEO knows a thing or two about building a company.

In a recent interview with Y Combinator, Zuckerberg offered advice for aspiring entrepreneurs.

Don't set out to build a company, he advised. Rather, "start with the problem that you're trying to solve in the world. … The best companies that get built are things that are trying to drive some kind of social change, even if it's just local in one place."

You have to pinpoint exactly what you want to do above anything else, Zuckerberg emphasized. Yet, "people decide often that they want to start a company before they decide what they want to do. And that feels really backwards to me."

And don't just identify any problem to solve — pick something you truly feel passionate about, he encouraged.

"For anyone who's had the experience of actually building a company, you know that you go through some really hard things along the way, and I think part of what gets you through that is believing in what you're doing and knowing that what you're doing is really delivering a lot of value for people," Zuckerberg explained. "And that's how the best companies end up getting made."