Single seller - Google commands 2/3 of search engine volume [1] and 1/3 of online advertising [2]. Yes, they have competition, but in several verticals they are the only practical choice. Note that this does not make them an abusive monopoly, which is what those characteristics seem to be describing more than a monopoly per se.

[1] http://searchenginewatch.com/article/2289560/Googles-Search-...

[2] http://www.bloomberg.com/news/2013-06-13/google-is-projected...

In which verticals is Google the only practical choice?

Search engine marketing, for one.

But not search, like the original comment claimed?

... I'm actually surprised it's only 2/3. I mean, there are fringe geeks on DuckDuckGo, and IE Windows default search is Bing, but still I've never seen anybody IRL actually open anything but Google for a web search.

The Chinese use Baidu, the Japanese use Yahoo, the Russians use Yandex etc.

The more accurate list is the "Sources of Monopoly Power":

  * Economies of scale
  * Capital requirements
  * Technological superiority
  * Network externalities

All of these apply to Google, to some extent or another.

Physical strength is one source of bullying power. Would you say that anyone who is strong is a likely bully?

I think you are conflating a monopoly with the abuse of such.