The most useful, informative, super-awesome site in the world is absolutely valueless if no one knows it exists. How do people find websites? Most of the time, by searching google.

This little trend in internet user behavior has spawned the sub-science of search engine optimization- Optimizing websites to attain the highest possible page ranking in google and, to a far lesser extent, every other search engine in existence. One of the crucial parts of optimization is providing text content that will be best indexed by the "robots" sent out by google to crawl the web and find stuff.

So we're not just writing for other people, but for robots, too. It has to modify the way people use language to communicate across the web. This article gets more in-depth on this nebulous quasi-science.