Mozilla has chosen Yahoo as the default search on the Firefox browser, ending a long-standing relationship with Google.
The firms have entered a five-year agreement, one of the most significant in recent years for Yahoo, and promise a number of positives for web users.
"Today, I'm thrilled to announce that we've entered into a five-year partnership with Mozilla to make Yahoo the default search experience on Firefox across mobile and desktop," said Yahoo CEO Marissa Meyer.
"Mozilla is an inspirational industry leader who puts users first and focuses on building forward-leaning, compelling experiences.
"This is the most significant partnership for Yahoo in five years and we're so proud that Mozilla has chosen us as their long-term partner in search."
Meyer added that engineering teams from both sides worked on the merging of browser and search and that US users will start to see the benefits first.
"Our teams worked closely with Mozilla to build a clean, modern and immersive search experience that will launch first to Firefox's US users in December and then to all Yahoo users in early 2015," she said.
"Search inspires us because we think it's something that will change and improve dramatically, and because, fundamentally, search is about human curiosity - and that is something that will never be finished."
Mozilla is equally effusive, saying that, when its decade-long search deal with Google ended this year, the company immediately began looking for an alternative to help meet its goals and ambitions.
Chris Beard, CEO at Mozilla, said that as well as bringing Yahoo search to Mozilla the firm is also providing Do Not Track features.
"Each of the partnership options available to us had strong, improved economic terms reflecting the significant value that Firefox brings to the ecosystem. But one strategy stood out from the rest," he added.
"We are ending our practice of having a single global default search provider. We are adopting a more local and flexible approach to increase choice and innovation on the web, with new and expanded search partnerships by country."
While Yahoo is the default option, Firefox will retain options for DuckDuckGo and Google.
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