This, along with !bang syntax and respect for privacy is what makes DDG my favourite search engine.

I really love typing "Maxwell's equations !w" or similar if I know I want the Wikipedia page for it.

Although the search results aren't always perfect (I still use Google occasionally, especially for non-English queries) these features are truly killer.

Learned some !bang shortcuts and it saves me time every single day. The cheatsheets are good too and having StackOverflow answers pop up at the top is also a great way to quickly get the right info.