Search Engine Technology

Search engines — all of us use them and rely on them to find what we want on the Internet.

DELFI Software deals with the development of the Search Engine Technology. We develop separate modules and whole products that go searching and immediately find what you need. Our technology is applied in Information portals and Business solutions.

Challenges faced by search engines:

• The web is growing much faster than any present-technology search engine can possibly index.
• Many web pages are updated frequently, which forces the search engine to revisit them periodically.
• The queries one can make are currently limited to searching for key words, which may result in many false positives.
• Dynamically generated sites may be slow or difficult to index, or may result in excessive results from a single site.
• Many dynamically generated sites are not indexable by search engines; this phenomenon is known as the invisible web.

Different Systems

Web search engines work by storing information about a large number of web pages, which they retrieve from the World Wide Web itself. These pages are retrieved by a web crawler — an automated web browser which follows every link it sees. The contents of each page are then analyzed to determine how it should be indexed. Data about web pages is stored in an index database for use in later queries. Some search engines, store all or part of the source page as well as information about the web pages, whereas some store every word of every page it finds.

When a user comes to the search engine and makes a query, typically by giving key words, the engine looks up the index and provides a listing of best-matching web pages according to its criteria. Most search engines support the use of the boolean terms AND, OR and NOT to further specify the search query. An advanced feature is proximity search, which allows you to define the distance between keywords.

The usefulness of a search engine depends on the relevance of the results it gives back. While there may be millions of Web pages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others. Most search engines employ methods to rank the results to provide the "best" results first. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one engine to another. The methods also change over time as Internet usage changes and new techniques evolve.