If I put 20 links to different websites on each one of those websites, will it improve the page rank of all of them? One of those sites has a PR4 and another is PR3 and PR2 on another page. Will this help all the sites' page ranks? will it worsen the ones that have the PR?
Internal Linking is one of the SEO strategies. I believe it could help you achieve good rankings. There's no harm with internal linking.
I'm thinking that you're saying the links are external - to 20 "different" websites... are all 20 interlinking with eachother? External links seem to get pr from the page that has them listed but the common feeling is that 10 - 15 is more than enough... it's thought that each link gets a percent of the pr of the page that it's on so there isn't much pr to be gained by a pr4 pr3 pr2 pr1 site - especially with 20 outbound links. The other thing is that if all the sites interlink with eachother then google will figure that out and devalue the link slightly It's also thought that links exchanging links with sites on the same c block of ip address is devalued as well - although - I have suspicions on that - after all, if your hosting is with godaddy or other shared hosting you're going to be on the same block with all kinds of sites you have no control over - how can you be penalized for getting a link on a site that just happens to be your neighbor?... but that's what they say. Lisa
Yes, what i am trying to say is that I have 20 different websites with different URLs and that will have a footer on each page that link to each of the other URL's one site has a PR4, and one has PR3 and subpage PR2. Will this idea help raise the PR on all 20 sites, and can it hurt the PR of the sites that have the PR?
Building up a spread of external links will help your site, try to get listed on a mix of sites with good page ranking rating
I think you should try and put occasional links in the text if possible, on one or two appropriate pages rather than site wide. Search for a post by Tyler Banfield here from a few days ago that talked about this - he suggested a one-way linking strategy that looked worthy of considering. If not now then soon google will not fall for the 'multiple links in the footer' approach. Even now it is not the best approach to take.