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.
Search Engine. A search engine is a web site that collects and organizes content from all over the internet. Those wishing to locate something would enter a query about what they'd like to find and the engine provides links to content that matches what they want. Google.com has become the most widely used search engine on the Internet.