When you buy links on high PR site or advertise your website on a good PR site then it is considered to be more effective. Such a website enjoys a better traffic and you can divert some of that traffic to your own website as well. It is also considered to be good for your google ranking and helps in improving it. By buying links on high PR site it means buying the space with these sites. When you buy the link space for advertising your link then you are basically able to highlight it more so that it is noticed by everyone and brings them to the website.
When the advertisers use buy links on high PR site then they are also able to get a good ranking, this is because the links are recognized as back links by the web crawlers. The web crawlers or the spiders are the tools which are used by the search engines to determine the ranking of different sites. They crawl through the high PR site and acknowledge the back links that are submitted on those sites and then rank it accordingly. You can get to create better links by opting for online media companies that can help you to submit your backlinks easily.