Taking someone else's startup idea and making it better might sound like cheating - but it's exactly how the most successful founders work

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It's a smart strategy. AOL cofounder Steve Case pictured.

• AOL achieved tremendous success by picking up where other internet startups had left off.
• That's according to Jean Case, a former AOL exec and the author of "Be Fearless."
• In turn, Case writes, contemporary tech giants like Google and Facebook have benefited from AOL's innovations.

AOL was built on the backs of other businesses' failures.

And as former AOL executive Jean Case writes in her new book, "Be Fearless," the company's ability to pick up where others had left off was nothing short of brilliant.

Earlier in her career, Case worked at a company called The Source, which she describes as "a text-based information utility for consumers that featured early versions of email, conferencing, and content." While the service was unthinkably slow by today's standards, Case writes that the concept behind it "was a really powerful idea, democratizing access to information and communication."

It just needed the proper execution.

After The Source failed to take off, Case moved on to the company that would become AOL. It was founded by Steve Case (Jean Case's husband), Marc Seriff and Jim Kinsey - three founders who'd already experienced their own series of business failures.

The previous iteration of the company, Quantum Computer Service, had been a partner of Apple's, until so much conflict led Apple to back out of the deal, as Steve Case writes in his 2016 book, "The Third Wave." From that experience, the founders learned that they wanted to create their own brand and pay for their own marketing.

QCS' service was rebranded as America Online in 1989.

Read more: Billionaire AOL cofounder Steve Case says he waited 10 years for the moment he realized his company was a success

As Jean Case boasts in the book, AOL had nearly 30 million subscribers at its peak and was the first Internet company to go public. She writes that Steve Case "led the team to experiment in areas that had previously limited growth for our competitors," including consumer-friendly pricing and membership plans.

In turn, today's tech giants found success by modeling themselves at least partly after AOL.

Case writes that Facebook, Google, and Twitter "all benefited from the innovations that AOL introduced." She adds, "Innovators can take major leaps or make a Big Bet by looking at where previous efforts feel short, and fully exploiting the lessons of those failures."