DuckDuckGo is a search engine that can be a great alternative to Google.The main reason is that Google keeps a track on what you are searching and provides Ads that are modified according to your tastes. Thus,there is a risk to your personal information if you are searching by signing in your Gmail account.
DuckDuckGo,on the other hand,doesn't collect any such information about the user and provides the results. Another feature of DuckDuckGo that its users swear by is !bang feature.
You can search Any Website like Facebook using DuckDuckGo by just typing !Facebook. The search engine will filter the results and only show the ones from Facebook.
Others complain about the results being not as good as Google, but I think they're just more used to interacting with Google. I'm fully acclimated and Google feels inferior.
DuckDuckGo stands #324 in the world as of this writing.