Natural are considered links, which are created by owners donor sites not for money by agreement with the owner acceptor, and on their own initiative - as a recommendation to visitors of their resource.

Most often, natural links are unlawfully.

Search engines highly value the availability of such external links at the site that participates in ranking and add additional rating points for each of them to him (depending on authority donors).

In addition, natural links help establish stable traffic, consisting of target audience, that improves behavioral factors and indirectly positively affects the website promotion process itself.

Fortunately, search engines have not yet learned to thoroughly determine the naturalness of links. Therefore, even purchased links with high-quality and, most importantly, thematic resources that have not “fallen” in the reference trade are in most cases perceived as natural. And the enterprising people successfully use it SEO optimizers, by creating a natural link profile for promoted websites using “right” purchases.