"DuckDuckGo gets its results from over one hundred sources, including DuckDuckBot (our own crawler), crowd-sourced sites (like Wikipedia, which are stored in our own index), Yahoo! (through BOSS), Yandex, WolframAlpha, and Bing."
"Because of our belief in a better search experience with less clutter, our ads have always been extremely minimal, unintrusive, and clearly marked as different than the other results." ついでにduckduckgo は設定で広告をオフにできる(検索バーからの検索とかはまたアレ