client=firefox-a is the string which brings millions for Mozilla Foundation as DI speaks about it. He says that Mozilla proves that there is big money involved in free and Open source. It is also told that the developers of Firefox browser generated $53 million in the year 2005 mostly from “search engine relationships” and most of the times money came from Google as it is the default search engine in Firefox.
Whenever you make a search by typing anything in Google search box inside the Firefox browser present at top-right, the search string is generated like –
The string present in the last – client=firefox-a is a hidden parameter passed from Mozilla to Google to tell that search is made from Firefox browser and now if user clicks on any ad from Google Advertisements, Google gives commssion to Firefox.
Similarly for IE 7, it is – sourceid=ie7 and for Opera, sourceid=opera. And if you want Google stop paying money to Firefox, you can use a small hack as follows –
Open Firefox installation folder (default is – C:\Program Files\Mozilla Firefox), edit google.xml and replace firefox-a text in it with any other string.