Since it was first published in 2011, The Lean Startup by Eric Ries has revolutionized the way countless entrepreneurs think about growing their businesses. Ries opens his widely influential book by describing his own early failure as a startup founder (and how emotionally devastating that failure was). What Ries learned was that having a great idea and working tirelessly are not enough to drive success. You need a structure, and "The Lean Startup" offers a great one.

"Startup success can be engineered by following the right process," Ries writes, and "It can be learned, which means it can be taught."

Ries stands up against time-consuming plans that go untested until a product or service is actually launched. Instead, he believes in building things in small batches, and then testing them to learn what customers want and don't want.

Here are three of the most important concepts in "The Lean Startup":

1. Get Comfortable With Uncertainty

Adopting many of the principles of "lean manufacturing" (a renowned method developed by Toyota), Ries's general approach to business favors building small. Building small means failing small, which allows you to learn lessons at a low cost — and put into motion a perpetual cycle of learning and improvement.

Ries stresses that business owners cannot be certain about what their customers want. He defines a startup as "a human institution designed to create new products and services under conditions of extreme uncertainty."

2. Build-Measure-Learn

Don't spend months building a multidimensional product and then distributing it in high volume only to find it's not what people want. That's an expensive, time-consuming mistake. Start small and make things in small batches. Then collect feedback and integrate that feedback into the next iteration of the product or service. Ries asks entrepreneurs to turn ideas into MVPs, or "minimally viable products," at a low cost and then measure how customers respond to them. The idea is to keep the build-measure-learn feedback moving all the time.

3. Redefine "Success" As Learning

Ries doesn't speak of "failure," but of "learning." Maybe you built a product and then tested it, assuming customers would respond a certain way. If customers responded differently, you didn't fail; you learned more about what customers don't want, and now you can apply those lessons in the next iteration. If "The Lean Startup" stands for anything, it's "validated learning," which happens by "running frequent experiments that allow entrepreneurs to test each element of their vision."

"The Lean Startup" is not just for new ventures. There's plenty for even the most seasoned small and mid-sized business owners to learn from Eric Ries's vision of continuous innovation.

Tags: small business Success