They are called white in contrast to the gray and black, using illegal techniques SEO promotion. In other words
Website Promotion
Website promotion is a set of measures for attracting targeted traffic. Often under website promotion we mean only search engine promotion (synonymous with SEO-optimization) – a set of measures that are carried out to improve the visibility of the site in search engines
How to use social networks to promote the site
Independent or professional promotion of the site with the help of social networks is becoming increasingly popular.