  Indexing the Web is becoming a laborious task for search engines as the Web
exponentially grows in size and distribution. Presently, the most effective
known approach to overcome this problem is the use of focused crawlers. A
focused crawler applies a proper algorithm in order to detect the pages on the
Web that relate to its topic of interest. For this purpose we proposed a custom
method that uses specific HTML elements of a page to predict the topical focus
of all the pages that have an unvisited link within the current page. These
recognized on-topic pages have to be sorted later based on their relevance to
the main topic of the crawler for further actual downloads. In the
Treasure-Crawler, we use a hierarchical structure called the T-Graph which is
an exemplary guide to assign appropriate priority score to each unvisited link.
These URLs will later be downloaded based on this priority. This paper outlines
the architectural design and embodies the implementation, test results and
performance evaluation of the Treasure-Crawler system. The Treasure-Crawler is
evaluated in terms of information retrieval criteria such as recall and
precision, both with values close to 0.5. Gaining such outcome asserts the
significance of the proposed approach.
