Because unlike Google, it doesn’t track me.

Your search history tells a lot about you.
And can be traced directly back to you.

From their site:

Other search engines save your search history. Usually your searches are saved along with the date and time of the search, some information about your computer (e.g. your IP address, User agent and often a unique identifier stored in a browser cookie), and if you are logged in, your account information (e.g. name and email address).

With only the timestamp and computer information, your searches can often be traced directly to you. With the additional account information, they are associated directly with you.

Results come from about 50 different sources such as Yahoo!, Wikipedia, Bing, and its own web crawler DuckDuckBot.

It also deletes results from content farms – low quality sites that turn out 4,000+ articles per day, designed specifically to rank well in Google.

Above is a typical results page.

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Image results.

You can set it to be the default search engine in both Safari and Firefox. And also iOS: Settings > Safari > Search Engine > DuckDuckGo

Try it out – DuckDuckGo.com