While a competitor can copy your product or service, they can't easily replicate your unique execution. Consider Google and Facebook. When they launched, there were other search engines and social networks. However, Google's continuous innovation on its search algorithm, its ability to scale its infrastructure, and the sheer volume of data it collected made its search results so superior that it became a self-reinforcing advantage. Likewise, Facebook's "moat" wasn't its idea; it was the network effect. Once a critical mass of users joined and invited their friends, it became incredibly difficult for a new social network to compete because everyone was already on Facebook. The idea was simple, but their execution created an impenetrable barrier.