Mozilla, developer of the Firefox web browser, has been mostly funded by Google for the last decade. Between 2005 and 2011, the search giant slowly ramped up its contributions from around $50 million USD for a single year to just over $100 million for the last year. All of this money was to keep the default search engine set to Google for the location and search bar. At that time, journalists were voicing their concerns that Mozilla would be cut off after the success Google saw with their Chrome browser.
In December 2011, Google and Mozilla surprised the world with a different announcement, $300 million dollars per year until November 2014, or almost three times their previous annual contributions. I could not help but feel it was like a light bulb that flares before it extinguishes, although later rumors claimed that Microsoft and Yahoo drove up Google's bid with high counter-offers. Of course, that deal ends this month and Google is no longer the winning bid, if they even proposed a deal at all.
This time, Yahoo won for the next five years (in the US) with a currently undisclosed sum. Yandex will be the default for Russia, and Baidu has been renewed as the default in China.
Yahoo also committed to supporting the Do Not Track (DNT) header for Firefox browsers. If your settings have DNT enabled, the search engine will adjust its behavior to acknowledge your request for privacy. One thing that has not been mentioned is how they will react to your request. This could be anything from treating you as completely anonymous, to personalizing your search results but not your ads, to personalizing your ads but not your search results, to only looking at the geographic location of your IP address, and so forth.
The search experience is not what you will get by going to the Yahoo homepage today; the new site was developed in collaboration with Mozilla and will launch for Firefox users in December. It will go live for every other Yahoo user in 2015.