Wikipedia:The answer to life, the universe, and everything

Significant coverage
We need significant coverage. We need multiple sources that discuss the topic directly and in detail. Not: passing mentions, directory listings, government records, or any old thing that happens to have the topic's name in it.

Reliable sources
We need sources that are reliable. Usually this means that the publisher has a reputation for fact checking and the text must be approved by an editor before it is printed. For example: books from reputable publishing houses, mainstream newspapers, or other periodicals. Not: tabloids, discussion boards, fansites, social media, or most blogs.

Independent sources
We need sources that are independent from the subject of the article. Not: books or articles written by the subject (including interviews), articles paid for by the subject, press releases, a Q&A interview where virtually all of the information is just the subject or a spokesperson speaking for themselves.