Today, the world wide web can be used both to 1 information and to make it 2 to others. Information 3 on webpages is viewed by 4 of browser. The sources of information linked in this way can be located on any computer 5 is also part of the web. Each information source 6 to an indefinite number of other webpages. Hypertext and hyperlinks allow users acting as receivers of information to 7 from one source of information to another, 8 for themselves which information they wish to 9 to their browser and which links they want to 10. The addresses of webpages can be found by using the many hundreds of general and specialized search engines which provide 11 to databases which hold information on them. Once a webpage has been found, hyperlinks may point 12 other places 13 interest on the web. Addresses of webpages also 14 in other more conventional media, such as magazines, newspapers and television programs, and on posters. Webpages, in their 15, facilitate access to information made available by other 16 of media, for example, collections held in libraries or programs broadcast on television. 　　Most webpages offer interactive opportunities which go 17 merely allowing visitors freedom as to when and how they visit a page and where they might choose to go next. Feedback can be kept formal via a questionnaire which can be filled 18 , or informal by providing an address for e-mail or even by 19 a digital guest book for comments left for other users to read. Although all webpages are protected so that unauthorized visitors cannot make unsolicited changes to them, it is also possible to 20 access to pages on the internet to those holding a password.