The words “successful startup” seem pretty straightforward at first glance. But, what do you picture when you hear them? A unicorn? A world-famous company, like Twitter or Facebook? A small company bootstrapping and grinding through the night, with steady growth? A lifestyle business? A thriving brick-and-mortar shop? A string of failures, followed by the perfect product/market fit?

Like so many things in the startup world, the definition of what a successful startup truly is can be elusive — and frustratingly subjective. While some founders might strive for that billion dollar valuation, others measure their success by how happy their customers are or the biggest impact they’ve made on the world. When we dig past the visions of unicorns da...