In addition to the network effects mentioned elsewhere: capital-intensive businesses that have raised significant capital and have a head start have moats.<p>So for instance, the reason a power company is a natural monopoly is that power transmission infrastructure is massively expensive to build, and the first one to raise the capital and build it out has a moat.<p>The same applies to something like video hosting that requires massive infrastructure (tho less so now than 15-20 years ago when YouTube was getting established.)<p>Or AWS — it takes massive capital to compete with them head to head, and even Google hasn’t entirely succeeded at that. (Microsoft sort of has, but mostly because their proprietary OS that’s so heavily relied on by enterprise is its own moat.)<p>Marketplaces are network effect adjacent. The reason no one really competes with Amazon (or in their niches, eBay or Etsy) is that all the buyers and all the sellers are already there. Same for Uber and Lyft.<p>IP is a type of moat for content based businesses like TV streaming services (Disney, Netflix, etc).<p>Apple tries to use the ubiquity of its devices as a moat for its services and massively profitable app store — though it’s a weak moat for the services and starting to be weakened by antitrust laws for apps/IAPs.<p>Technical moats, well… some tech expertise isn’t sufficiently widespread that any upstart competitor can hire someone to do the work. If you want to compete with Nvidia, good luck hiring all the world-class experts you’d need.<p>Microsoft’s moat? Switching costs, including learning curves. And all the software written specifically for Windows that’s not available on other platforms.<p>Switching costs are also a major moat for an email service like Gmail.