1. A method of navigational ranking for focused crawling, comprising: using a classifier to distinguish at least one target web page from other web pages on a website; modeling the web pages on the website by a directed graph G=(V, E), wherein each web page is represented by a vertex (V), and a link between two web pages is represented by an edge (E); and assigning each web page (u) in V a weight p(u) based on the classifier to calculate a navigational ranking indicating relevance of a web page.