What is Link Juice

A major factor in ranking for competitive keyphrases in SERP's (search engine results pages) is obtaining links that pass juice.

Juice can be defined as a link that passes the authority, reputation, and topical information included in the anchor text and in neighboring text and links.

Nofollow
When a link is created an attribute called nofollow can be included that indicates to search engines that the link should not influence indexing or rankings. The search engines all treat nofollow in different manors.

Javascript
A link can be placed on a page using Javascript rather than html. These links are not spidered in the same manor as html links.

Do all pages pass link juice
No. Google and the other major search engines will penalize sites and pages if caught selling links, allowing spam links, linking to bad neighborhoods, and other issues that break their terms of service or adversely influence TrustRank.

For this reason, you should be very selective when making reciprocal link agreements and paying for reviews to be placed in directories.

Google and the other major search engines respect, and therefore pass link juice on the Yahoo directory and others that are selective in their acceptance policies and don't allow free for all anchor text titles.