Authority is an important factor in SEO: both external and internal links are a recommendation. More links to a page means a higher popularity. It is important that it left concerns of qualitative websites. Preferably with a high popularity, in line with the content of a Web site (links). Usually we talk about external links, which are links from other external websites. Internal links are also very important. If many pages within a site refer to a specific internal page, then that page has high internal link popularity. A good internal linking structure is therefore essential, so important pages come forward and the focus is not less important pages. Within link popularity, the guidelines of Google: provide paid links should not contribute to the link popularity, the links have a nofollow tag do not count in the link popularity, link farms are not allowed, anchor text (the text to which a link will be linked ) are very important and an unnatural pattern of getting links may punish Google with a penalty. There used to obtain authority especially from link building.