In this paper we study in what order a crawler should visit the URLs
it has seen, in order to obtain more "important" pages first. 
Obtaining important pages rapidly can be very useful when a crawler
cannot visit the entire Web in a reasonable amount of time. We define
several importance metrics, ordering schemes, and performance 
evaluation measures for this problem. We also experimentally
evaluate the ordering schemes on the Stanford University Web. 
Our results show that a crawler with a good ordering scheme can
obtain important pages significantly faster than one without.