In the recent time we have seen the rise of various full text search programs performing search of documents in various formats, information in DBMS and informational systems, email messages and other data stored both on the hard drive of a personal computer or in the local network of an enterprise, as well as in other sources of knowledge.

The need for such search engines is conditioned by an on-going growth of textual information bulk available both to the whole society, and to each of its representatives. While until recently the full text search tools were aimed at the corporate sector (for the purposes of home use "direct search" with conventional browsing through each file was quite sufficient), now developers are working towards meeting the needs of a conventional user. After all, the bulk of information has soared. Nevertheless, the priority tendency of developing full text search technologies (in addition to the Internet) is the corporate sector.

The most important parameter of any full text search system is the speed of its operation. This relates both to indexing large amounts of data and to the speed of searching documents. It goes without saying that a highly important factor is the ability to work with various data sources, lists of supported file formats and additional functionality (support of morphology, synonyms, and various types of search). However, when you consider a certain set of required functions, the overwhelming majority of competitive information retrieval programs boast of them all.