When you want to search for something on the Internet, most people go to Google without even thinking about it.
When I want to buy something on the Internet, my default behavior is to go to Amazon and search for it.
When my kids want to get tix for a concert, they go right to Craigslist and post a ticket wanted listing and search for a seller.
These are 'default behaviors'. We do these things by second nature without even thinking about it.
Only they didn't. Somehow they got to be the default. Most often by being sufficiently superior to the other services of their kind. Or in some cases, by simply being first and building up a network effect or a data asset that was unassailable by newcomers.
But however a web service attains default status, it is a hugely valuable position to secure.
Default positions can be lost but not easily. Most often they are eroded by new web services that cleave off parts of their functionality. Less frequently are they just replaced by a newcomer.
If Google's power over the web wanes, and I think it will in time, it will not likely be the result of Microsoft or someone else replacing it as the default search service. It will be because new default functions emerge that lessen the number of times we want to use the search function.
So what does this mean for entrepreneurs and VCs? Well for one, don't make a frontal assault on a default service. Build or finance a service that can become a new default function in the Internet operating system. And if you have a shot at becoming one of these default functions, invest all of your time and energy attaining and solidifying that default position before working on monetizing it. Because its a very tough position to secure and once you get there it's pretty hard to knock you out.