Many webmasters buy PR for their site. They find a site that has a PR of 8 for example and buy a link to their site. After a while, your site ends up with a higher PR and you in turn can sell PR or the site in whole; provided the site you are buying from does not have Fake PR. Google turns this kind of PRs as a fake PR.
Ya, apex.tech is wrong on this one, fake PR is when you do a redirect to a site with higher PR during the PR update. At this point, that site's PR will transfer to yours. That is fake PR, what you are talking about is just link building
but doesn`t the google bot see that you redirected it to another domain during the page rank update. Like this I make 10 blogs and redirect them to pr5-pr6 domains and the sell links and get rich .