First of all, thank you SO much for clarifying my question! It is part of an overall essay topic that I can't figure out how to answer:

Question

Compare and contrast the methods used by late nineteenth century corporations to control competition - especially the pool, trust, holding company and vertical and horizontal integration.

I don't understand the difference between horizontal and vertical integration. I kind of see some of these things connecting because of their unifying companies to be able to reduce competition to be able to raise prices, like you said. But isn't that the topic of the essay? And aren't all of those methods similar in that way? I don't feel very insightful right now.

Yes. These methods are similar. I think that's the point of your assignment -- to find the ways they are similar and the ways they are different -- and then apply them to the late nineteenth century.

The two Wikipedia sites linked below define most of these terms and give examples. For instance, the Carnegie Steel Corporation used vertical integration to help achieve its goals. I didn't find much about pools, but the last two sites have some information about them.

http://en.wikipedia.org/wiki/Vertical_integration

http://en.wikipedia.org/wiki/Monopoly

http://www.liheap.ncat.org/iutil2.htm

http://www.answers.com/topic/pool