Over the last 30 years man-made CFCs have been the main cause of stratospheric ozone depletion. CFCs however, are not the only ozone-depleting chemicals. Other ODCs include the methylhalides, carbon tetrachloride (CCl4), carbon tetrafluoride (CF4), and the halons which contain bromine instead of chlorine.
Part of the Internet applications glossary: Yahoo! is an Internet portal that incorporates a search engine and a directory of World Wide Web sites organized in a hierarchy of topic categories.
However, a Meta search engine is such a search engine that collects data from other regular search engines, consolidate the gathered results and show them to the user. That means, there is a high probability to get more and refined result from a Meta Search Engine. The Architecture of Meta Search Engines