1. Document Inception Date
The document inception date is the date the document was created, first indexed or linked to or the first registration date of the domain. The inception date is used to determine the rate of growth of links to a document. For example, a document with yesterday's inception date with 10 links to it could be scored higher than a document with an inception date of 10 years ago and a 100 links to it. For some searches that are made on a search engine, an older document may be more favorable than a newer document therefore older documents may be ranked higher and vice-versa.
Additionally to this, proper navigation allows search engine spiders to follow your links and put your pages into their database. People need to find their way around your site, as well. Sometimes, organization is what distinguishes a high quality site from a loser. A well designed navigational system will have a positive impact on search engine optimization.