There are many methods of SEO. For a general website, the optimization of external links accounts for about 50% of the entire SEO process. Therefore, how to build external links is the most concerning issue for us webmasters and SEO marketing personnel. External links mainly have two forms of expression: one is URL link, the other is anchor text link. The main function of URL link is to speed up the inclusion of the website, while the main function of anchor text link is to improve the keyword ranking. The function of anchor text link is better than that of URL link, because the anchor text link not only contains all the functions of URL link, but also plays a role in improving the keyword ranking. Generally speaking, only clickable hyperlinks can be considered as effective external links, and a non-clickable URL in text form does not count as an effective external link.