Google and Mozilla, the company behind Firefox, have signed a deal that will keep Google as the default search engine within the open-source browser.

The last deal, signed in 2008, ran out in November 2011; however, during that time Firefox has seen some decent growth with the backing of the search giant.

This renewal should come as a great relief for those at Mozilla, as the deal was seen as crucial in the continued success of Firefox - Google is, by far, its biggest source of income. Such dependence, however, isn't exactly healthy for any company, especially as Google has its own browser in the shape of Chrome.

It is curious then that Google should see it as necessary to go in with Mozilla again, although in view of its recent troubles with anti-competitiveness charges, it could be a rather shrewd move.

In light of its clear dependency,  Mozilla brought Microsoft's Bing on board recently, both as an optional browser and as a default, and it seems for now at least Mozilla has some breathing space.