1: If the owners take the initiative to give each other one-way link, do not go back to the backlinks, which would be the best outside the chain. Link, however, the right to exchange links weight is relatively lower than the one-way links, so that one-way links are relatively rare, because of this, he is also the most valuable. 2: usually webmaster editing articles, voluntary provide an outer chain pointing to your site is well external links. When edit article mentioned a concept about your site and your site is more comprehensive, the most authoritative, direct link to your website. This form as the meaning of voting. 3: anchor text links to improve the site's ranking account for a large proportion. Excessive concentration of anchor text links often lead to one of the search engine penalties if a home outside the chain are basically the same anchor text, usually also the most important keywords website. A clear violation of the search engine's "natural" law, but let the search engine that is optimized excessive. This small suggestion: do anchor text links, can communicate with each other webmasters, update site content, the article referred to the other key plus anchor text links. Interchangeable with each other, but also a good method. 4: When the SEO workers say a page is handled about 400 calls, and do not necessarily credible. But when some enterprise managers and 400 phone users say that a page is handling about 400 calls a more credible. External links of traffic sources, whether the content is very important. Although no clear boundaries to determine the content relevant, can only rely on intuition and common sense, can not know exactly free telephone call transfer center, China Unicom, which in the end with 400 calls handled more, but at least know that these themes more than beauty, fitness and relevance of the 400 calls handled. 5: The weights are usually most concerned about the problem of looking for the source of the outer links. Pr value of the site and how site rankings, also will have a direct impact on the effect of the outer chain. The better the ranking, the weight of the other sites is also higher, not to say that trying to find the other site's ranking in the home page or the top 20, even if the first few dozen pages also have some weights and ranking ability.