In addition to PageRank , Google , over the years , has added many other secret criteria for determining the ranking of pages on result lists , reported to be over 250 different indicators , the specifics of which are kept secret to keep spammers at bay and help Google maintain an edge over its competitors globally .
In addition to PageRank , Google over the years has added many other secret criteria for determining the ranking of pages on result lists , reported to be over 200 different indicators .