Methods of optimization, online promotion through links purchased / sold are still practiced and promoted as online marketing strategies that guarantee spectacular results at least in attracting traffic, ranking higher in search engine, increase sales, and so on.
There are still SEO specialists who continue to propose and sell link building strategies that include such unnatural links: directory submission, advertorials and articles with countless backlinks, spam anchor text, comments on blogs and forums with links added randomly to the sites homepage several times, especially in a context unrelated to the site.
According to Google's quality guidelines, selling / buying links with PageRank transfer is considered a try to manipulate Google indexing and ranking algorithms. In these conditions sites that (sell) send to unnatural links, but those who (buy) get such links are penalized: the site loses Google confidence, loses position in search results pages (can be even excluded) and therefore, PageRank coefficient decreases.
When robots find artificial / unnatural links received from other websites or to other websites, you will be notified in the Webmaster Tools account, which cautions that you have lost Google trust and you are advised to clean the site of such links that try to manipulate indexing and classification algorithms.
What we do to remedy the situation?
1. In case of selling links
First you have to remove all the paid, unnatural links, including advertorials, or mark these links with the tag rel="nofollow". When we are sure that these issues have been resolved, we can send a request for reconsideration of the site in Webmaster Tools account. After manual analysis of the site, we get an answer on the accuracy of the website and cancellation or not of penalties until the problem is entirely fixed.
2. For those who bought links
The first step is to ask those who manage websites that send to unnatural links to eliminate them, or mark them with the tag rel="nofollow". It often happens that they are simply abandoned or we cannot contact the webmasters that manage a certain page. If you have received notification of artificial links in Webmaster Tools, but only in these conditions, we can use the tool provided by Google: "Disavow Links".
But let's keep in mind
Backlinks should be removed only after careful consideration, and after identifying those that really affect the site in a negative way.
And then comes the question: "So, we're not buying links, but how are we promoting the site?"
There are strategies and techniques for on site and off site seo optimization which bring excellent results and meet quality standards - technical and content – in search engines, effective methods of promoting social platforms that can bring real results, which are durable and without negative consequences for the website.
Such a strategy is guest posting, something that SEO professionals do. Using quality content which is relevant for the readers and adapted for each website, guest posting proves to be an effective way to gain higher positions in search engines. This is the natural way of making links, a method which respects the Google's principles.
Attached image source: Wikipedia