to Web dynamics or just due to bad Web sites In fact W eb sites in IN could be considered as new sites which are not linked because of causality reasons Similarly OUT sites could be old sites a darker color represents older pages The a verage case can be considered as the freshness of a site diagram for Set The colors represen t Web site age oldest a verage and new est page suc h that One of the initial motivations of our study was to see if the IN and OUT components were related which have not been updated Figure sho ws the relation between the macrostructure of the Web using the number of Web sites in each component to represent the area of each part of the distribution of the oldest page in each site for Set in eac h component of the Web structure versus while the newest page a measure of update frequency on a site Figure plots the cum ulative date in a logarithmic scale these curv es have the same shape as the ones in for pages The central part is a line and represents the typical power laws that appear in many Web measures site whic h is equivalent to the probability of being in any page of the site points to good content pages In the similar w ay a page will have a high authority rank if it is The hub and authority are complementary functions A page will ha ve a high hub rank if it point to page i and is the number of outgoing links in page j Lj When considering the rank of a Web site w e use the sum of all the ranks of the pages in the where q is the probability of getting bored t ypically with j mj referred by pages with good links In this w ay the authority of a page is dened as the sum of the the pages it points to hub ranks of the pages that point to it and the h ub rank of a page is the sum of the authority of dieren t parts there is a group of new sites but the majorit y are old sites Hence a large fraction increased whic h may imply a degradation of some part of the Web Inside the core MAINMAIN than Set the smaller percentage but it is larger as Set triples the n umber of sites of Set OUT also has of IN are sites that never became popular the sites in eac h component of the macrostructure of the W eb as w ell as the percentage change among both data sets in more than a year Although Set did not include all the ISLANDS at In Table w e give the numerical data for the average age as well as the Web quality sum for all Several observations can be made from Table First sites in MAIN ha ve the higher Pagerank MAINMAIN so the k ernel of the Web comes mostly from the past What is not ob vious is that Notice that IN has the higher hub which is natural because sites in MAIN have the higher authority on average sites in OUT are also newer than the sites in other components Finally IN sho ws two has increased in expense of MAINNORM Ov erall Set represen ts a Web much more connected component and that is wh y they are not linked y et The oldest sites are in MAIN in particular that time w e estimate that Set w as of the sites w e can compare the core The core has Here we obtain some conrmation to what can be expected The new er sites are in the Island MAIN has the largest authority This mak es MAINMAIN a v ery important segment of the Web and inside it MAINMAIN is the subcomponen t with highest Pagerank In a similar w ay MAIN we can make the following two observations where F j pages k linked by j f is the total w eight of the links in a page The result does agek not change to much but the computation is slo wer Yet another approach would be to study how good are the links based in the modication times t and t for P and P suc h that t t t Lets assume that P and P reference P Then of both pages involved in a link Suppose that page P has an actualization date of t and similarl y