"Usenet" provides a huge selection of discussion groups, and has been around many years, long before there was a World Wide Web or Web Browsers.
One way to find messages posted to a discussion group, based on word search, is to use the following, previously referred to as dejanews:
The term "Meta Search" refers to search tools that rely on multiple indexes of Web pages. These are sometimes called "Meta Crawlers".
If you want to learn more about the various search engines and indexes, visit the following Web site: