exact match domain (EMD)

If a search query contains keywords which match the DNS domain name of a website, without any extra words, it's an EMD — exact match (to the DNS) domain.

This was considered valuable by the Algorithm in its early years, and it probably was useful to people. Consider, if you want to find the SEO Jargon File, and you can remember our name, but you're not sure of the TLD (top level domain, in the case .com) you could query, "SEO Jargon File" and it would b helpful to you if this site appeared near the top of the search results page.

However, spammers noticed this and began registering a great many exact match domains for popular search queries, which they then populated with low quality ("information free" or "content free") websites that were nothing more than "click holes" to show advertisements.

In 2012 Google realized that this practice has grown so large that it was polluting the search results. The Algorithm was modified so that exact match domains no longer provide any benefit (or perhaps provide a benefit so small that it's difficult to measure).

For reasons unknown, the Bing search engine continues to award karma to exact match domains, so the practice continues, although the revenue stream from this noise pollution is likely reduced from pre-2012 levels by about 90% or more.