<p>You can start internships in high school. I grew up down the street from a kid that was interning at DHL North American headquarters in his junior year, though I qualify that by saying his parents had business connections.</p>
<p>Before you’re 18 you technically can’t enter into a contract, but that doesn’t mean you can’t start a business with your parents. The question of “what business?” is something hundreds of books, seminars and infomercials have dedicated themselves to answering (often poorly), and it’s impossible to tell you what business to start. Location, your skills, seed money (or lack thereof), your passions and the market all define whether or not you’ll be successful.</p>
<p>At your age I’d really just recommend reading and doing what you can with internships (assuming money isn’t an issue for you and you don’t have to work to actually support yourself in high school), and when the time comes and you’re in college you can throw around a few stupid startup ideas like everyone else does.</p>