The content of this section was brought over from Google Juice, as it may find partial reuse here:
Google Juice, sometimes contracted to GoogleJuice, is an ethereal substance that flows between hyperlinks on the Internet between web pages in both directions. Web pages with lots of interconnecting links on them get more Google Juice and are therefore likely to have a higher PageRank, a SEO measure which suggests how prominently a particular web page is likely to be after a given search. One definition suggests it is a "mysterious quality that causes pages to come up high in a Google search." Another source suggests that it is a slang term for PageRank, and a definition by Marziah Karch suggested the following:
One of the ways Google determines the relevancy of things you search for is by looking at all the backlinks, or the pages that link to it. It's like a popularity system based on hyperlink "votes." Not all backlinks are created equal, however. Pages with higher PageRank (more Google juice) transfer more relevancy to pages they link to. So rather than focus on sheer quantity of links, you should focus on the quality links and try to attract or create links from pages with the most Google juice.