If you buy backlinks in large quantities and receive a few back links from external websites, the received ones will be given more importance than the ones you bought. External back links are considered more important as they are given on the basis of trust and appreciation. Nowadays, webmasters have figured out techniques which can replicate an ordinary back link as an external back link. This is the reason why back links factor in so highly into a search engine’s algorithm. Webmasters have come out with techniques that automatically generate pages that act as back links to the original website. Hence you can buy back links and use them as external back links for your website. These pages are called link farms, and they are not only disregarded by search engines, but linking to a link farm could get your site banned entirely. As a result, nowadays, search engine’s criteria for quality back links have gotten even tougher.