Viral advertising — type of advertising material distributors which is the target audience, by creating content that can attract through vivid, creative, unusual ideas or using natural or confidential messages. To optimize the internal (concerning only the internal system of the site) — includes work aimed at the overall improvement of the quality of the site, the benefits that it brings to the visitor. With the advent of technology PageRank more weight was given to external factors that helped Google to become the leader of the search on a global scale, making optimization using one of the text on the website. The task of the copywriter is to write the original text so that such optimization was less visible as possible "live" to the reader (and in particular the assessor search engines).
Compliance of advertising materials and context of the sites is determined by the algorithm of advertising service.
Widely used also incorporating the key request in the HTML title tags, h1, alt, attribute meta keywords.