To read more about what made Trulia so defensible, visit:   / the-nfx-of-trulia-building-a-3-5-billion-m...  . This video provides a rarely seen perspective on the network effects that helped Trulia change an entire industry, eventually becoming one of the world's leading online real estate tools and merging with Zillow in a $3.5 Billion deal. Network effects are a type of defensibility, and founders would be wise to master how they work because in the end, defensibility is what matters most.