1.1 Relevance of the subject

Internet is becoming more and more our information provider. "In 2002 a
study from the U.S. Department of Commerce estimated that 36% of the American
public over the age of 3 used the Internet to search for product and service
information in 2001. This usage represented a substantial increase in information
search behavior from 2000, when 26% of the American public reported using the
Internet to search for product and service information."5
Between 2000 and 2008 the USA got an increase of Internet users of 130,9
%6 we can then imagine how important is searching information through Internet
nowadays.
The number of Internet users is estimated to 1,463,632,361 (world population
6,676,120,288) with a growth rate from 2000-2008 fixed at 305.5 %7.