No startup is safe from the threat of competition. But some more than others have managed to fortify their place in their market. 

Brian Halligan, CEO of HubSpot, a marketing software company, says that, today, this is accomplished through great marketing.

"What you want to do with your business is you want to build a moat around it. You want to make it ice cold. You want to put sharks in there, you want to put alligators in there," Halligan says, referencing advice from investor Warren Buffett. "Next year: colder. More sharks, more alligators."

Halligan tells entrepreneurs to think of inbound marketing as their moat.

"It's about brainpower and skill, and it's how to create a big barrier to entry against your competition," he says.

Halligan points to a concrete example. Why aren't new founders taking on e-commerce site every day? Any business savvy individual could figure out how to replicate the company's supply chain or website. 

"The reason that we don't start a company to compete with Zappos is not that," Halligan says. "The moat around their business is the two million links into their website. How are we going to do that? It's the 10 million Twitter followers they have, the massive number of Facebook likes. You can't wake up overnight and get that."

The good news for startups is that innovation in inbound marketing is just beginning. 

"It's the top of the first inning in this game. It's very early, so it's not too late to get going," Halligan says.

For more on establishing a strong marketing strategy, check out the video below.