Well, it's not quite that easy to invest like Mark, but follow through this link to get to the excellent speech. While we disagree with a few of Mark's points, this one certainly rang true:
The way I see it, there are really only four sources of economic moats that are hard to duplicate, and thus, long-lasting. One source would be economies of scale and scope. Wal-Mart is an example of this, as is Cintas in the uniform rental business or Procter & Gamble or Home Depot or Lowe's. Another source is the network effect, a la eBay or Mastercard or Visa or American Express. A third would be intellectual property rights such as patents, trademarks, regulatory approvals, or customer goodwill. Disney, Nike, or Genentech would be good examples here. A fourth and final type of moat would be high customer switching costs. Paychex and Microsoft are great examples of companies that benefit from high customer switching costs.
That passage is an excellent example of the types of companies you should be looking to invest in and yet something is missing: the fact that you need to identify these companies, and their moats, before others if you plan on making an excellent investment.