CFCs, HCFCs, and Halon: The ozone layer is destroyed by CFC's, chlorofluorocarbons, that are used as a propellant in aerosol cans, and refrigerants in older cars and refrigerators. When Chlorofluorocarbons (Freon and other CFCs) and Bromofluorocarbons (Halons) they became popular refrigerants and fire fighting agents.
Anyways, let's come to out topic. Yahoo! Browser. Yahoo is the No.1 site on the web. Having the maximum traffic, it's still ruling in the laexa rank. Now, just to get all it's pages open properly and work nicely, Yahoo! joined hands with Microsoft in making a Yahoo! friendly browser. And here it is, YAHOO! Browser.
Some people are brand loyal. They like Microsoft so they stick with the Bing search engine. They use yahoo mail so they search on Yahoo search engine. Often they accept the Bing default on the Internet Explorer browser. Some like the Bing browser interface - it looks pretty nice, actually.