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.
Google Search, commonly referred to as Google Web Search or simply Google, is a web search engine developed by Google. It is the most-used search engine on the World Wide Web, handling more than three billion searches each day. As of February 2016 it is the most used search engine in the US with 64.0% market share. The order of search on Google's search-results pages is based, in part, on a priority rank called a PageRank.