We can list some examples of moat:
1, the most unbreakable business moat is "networking effect", typical examples are ebay, more buyers to ebay brings more sellers, and more sellers to ebay brings more buyers, another good example are windows, windows is not a fundamentally good product but it occupies more than 90% OS markets, why? because of networking effect, more users uses windows, more applications are developed for windows, more hardware are produced for windows, and all these brings more users. Youtube is another good example.
Networking effect needs to have a critical mass, it is hard to predict before it reaches that. Current good candidates with strong or weak networking effects are: loop, ebay in financial real estate. adbl, online book download.
2. patents are good moat, this is easy to understand, all the biotech company work on this principle.
3. Every high time/capital requirement,
a good example is AKAM, it not only has a good algorithm for network traffic management, but also it has a network of servers around the world, there are more than 15,000 of them. It is very hard to build a similar network.
Railway network is almost impossible to build because of land price.
FMD is a specialist on student loan industry, it has the ability to assess the credit score of a collection of thousands of student loans. It has this ability because it can use a database with 40 years of student loan history. Big banks like bank of america, JPM does not have this ability, if I understand it right. So banks relies on FMD to do business for them. FMD signed up about 7 banks as its customers last year, growing earning like 80% last quarter.
4. Unique technology, example like google, this moat is not that reliable, if a smart guy comes up with a better search algorithm and find a strong financial backing, google empire can collapse overnight, although google can afford to buy it out.
5, low cost provider, walmart is a good example. This is very reliable advantage, I could not imagine anyone can compete with Walmart.
There are other moats, but these are on the top of my minds. As a longterm investor, I want to find companys with strong moat as earlier as possible and buy into them, sometimes even at higher above average prices. The key of moat analysis is to understand the moat, if you think the moat is unbreakable, but in reality, it breaks some day, then all your capital time investment will be damaged greatly. Also important in FA analysis is that estimation of a company's ability to develop business moat.