"Hummingbird," 2013: Gives preference to sites with clear conversational answers to query questions.
"Pigeon," 2014: Gives preference to search results local to the user so that, for instance, a search for restaurants would find ones in the user's neighborhood or current location.
Mobile Preference, 2015: Penalises sites that do not work well with mobile devices.
HTTPS Preference, date unknown: Gives preference to HTTPS sites, presumably because hackers are unlikely to pay retail for the necessary security certificates.
Engagement Preference, date unknown: "They won't say specifically what they are using to measure engagement," says Vanessa Fox of search analytics vendor Keylime Toolbox. "But does the site load quickly? Is it easy to navigate? Is it easy to get answers?"
Sign up for Computerworld eNewsletters.