Link Juice is the amount of positive ranking factor that a link passes from one page to the next.
A site has an overall Domain Rank. This is the total amount of positive link metrics associated with a website as a whole. The Domain Rank is determined by the combined PageRank of all of the individual pages on a website. Every web page will have its own PageRank determined by the link metrics associated with each particular page. It is the Link Metrics of any given page that determines how much Link Juice any one web page can pass to another.
Link Juice should be spread as evenly throughout a website as possible. A lot of websites make the mistake of focusing all of their link juice to their home page, with very small amounts trickling deep into the site. Obtaining deeper links has always been a good idea, however, since Google Panda, it is now an absolute necessity.
Link Juice Distribution
1. Don’t concentrate your link metrics on your home page.
Make an effort to weave in-coming links throughout your web pages, not focusing too much on any specific one. This is called ‘deep linking’, and is a positive ranking factor. Since Panda, it is even more important, with websites being actively penalised for having too high a concentration of links pointing only to their home page.
2. Pass Link Juice from high performing pages to low performing pages.
Link Juice can be passed internally. If there is a web page on your website that is performing particularly well, it is able to pass link juice to a web page that is performing poorly.
3. Use Robots Tags, Robots.txt and NoFollow Tags.
Using Robots Tags and Robots.txt is a good way to prevent search spiders from crawling and indexing low-value pages. Place the robot in the HTML of the page, instructing the search engine to either not crawl the page altogether or crawl but not index the page. You should also use the NoFollow Tag to instruct the search engines to not pass any link juice onto the page from any linking pages. NoFollow is not as effective as it once was, as the search engines do not pay attention to it nearly as much as they once did, but it is still a function worth utilising.