Spam is any unsolicited email you receive. People who send out commercial email are required to give you a way to "opt out," or unsubscribe.
People also use the term spam to describe any of the following:
- Web pages that appear high in search results but aren't really useful or pertinent to the search you've just made. Google changed its algorithm in early 2011 to address this problem.
- Comments on blog posts or news articles that offer no insight, new information or even real commentary, and were made solely to post a link to the commenter's website.