The tech world is full of stories about genius 20-somethings who started a company out of their garage or their dorm room that eventually became a multi-billion-dollar success. Google. Hewlett-Packard. Apple. Even Walt Disney started creating cartoons in his garage.

Reading their stories can inspire you to go after that dream you’ve been harboring or to chase your fortune. If they could start a company with a few hundred dollars and a vision, why can’t you? Here are the stories of three powerhouse companies that started from nothing to inspire you:

Pinterest

Pinterest is one of the fastest-growing sites, reaching more than 1 million users in its first 10 months. In fact, the site’s traffic grew 50 percent month over month in that first year.

The site was launched in 2009, and the girlfriend of founder Ben Silbermann came up with the name while they were watching TV. What set the site apart initially was its early adoption of the grid layout (the team spent a lot of time and money perfecting the design), its focus on community (Silbermann personally wrote to the first 7,000 users when they signed up), its exclusivity (you had to have an invite to join the site in the beginning), and its novelty (this was a site focused on getting you off the site and actually doing something).

Pinterest now has an estimated 70 million users worldwide and is valued at $11 billion.

Amazon

Jeff Bezo was tired of working on Wall Street, and when he heard a statistic that the Internet — still new in 1994 — was growing at a rate of 2300 percent per year, he started making a list of ideas for his own online company. He decided to start selling books since they were relatively cheap and in high demand. He started selling out of his parents’ garage in 1995. Within two years, the company had raised millions of dollars and was selling $20,000 worth of product per week.

Now Amazon brings in $61 billion a year selling everything from workout gear to sofas. The company employs about 97,000 people, and jobs there are in high demand. Many people actually get their foot in the door by working as temps at IT staffing companies like Kelly Services.

Facebook

The story of Facebook is famous — in fact, a movie was even made about it. Mark Zuckerberg was only 19 and a sophomore at Harvard University when the site was launched from his dorm room in 2004. The rest of the origin story in shrouded in scandal over whether or not he stole the idea from three other classmates who had allegedly approached him about developing a similar site.

Those allegations have never been proven, and Facebook has since become an indisputable success. Like Pinterest, Facebook had early success thanks to its exclusivity. Other social networks existed, such as MySpace and Friendster, but you had to have a college email to get onto Facebook. In the beginning, you could only get on if you were a student at Harvard — and later other Ivy League universities. Now everyone you know is on Facebook — or, more succinctly, 400 million people a month.

All it takes is one great idea and perseverance to create the next Pinterest or Amazon or Facebook. What idea have you been sitting on? Maybe it’s time to make it a reality!