Web search services are now a major
source of information for a growing number of people. Due to the
rapid development of the Web, Web-based search engines have become
the most important tools for accessing global information resources
on the Internet. Although these search engines are easily accessible
and highly popular, search engines technology, coverage and systematic
evaluation of their characteristic is not often presented to users.
On the other hand user need to know more about characteristics
of Web search engines to improve the effectiveness of information
retrieval. In the presentation general remarks and actual problems
with web retrieval will be given and the difference between "visible"
and "invisible" web will be emphasized. A short history of search
engines and recent tendencies will be shown. The main search engines
will be compared according to the most important evaluation criteria.
Meta-search engines intelligent agents and web tools will be analyzed
too. As the conclusion features, important characteristics and
future development of a search engines, which can provide high-value
results, will be presented.