DuckDuckGo's business-model?

Even though I use DuckDuckGo myself and like their different services,
I now and then gets overwhelmed with a sneaking doubt…

What is their business-model?
How do they make money? - I can’t throw dollars at them for email-forwarding or anything…

Clicking around on their website doesn’t help me with information.
Can someone with better eyes or google-fu help me with info…

Thanks in advance :slight_smile:

They have a page on that: