When you browse the Linux Mint websites without an ad blocker, you will see ads displayed on the pages. These are banners from the Platinum, Gold, and Silver level sponsors of Linux Mint
, and from ads from Google AdSense.
As to search engines, indeed some are partners of Linux Mint
or otherwise share part of their revenue with the Linux Mint project. You can read more about that here: http://www.linuxmint.com/searchengines.php
If you want, you are of course free to use an ad blocker to block ads and/or to use a different search engine. There are users that do that and then instead donate
to the Linux Mint project. The developers can't work full-time on Linux Mint if their families can't eat