to do the optimization, may know the content is king, the chain for the emperor this sentence, we can see the importance of the chain, Links as a chain, the weights of the website promotion, website keywords ranking, and enhance traffic plays an important role. Links can also make people all over the world to find your website, your website really become the waves never disappear. When people exchange Links, how to judge the quality of this website? If you look only at the other site the PR value, you obviously already outdated, many PR cost can hijack, how to judge what kind of website is worth to exchange? First of all to see the other side of the PR value, also should see the other side of the snapshot the best, snapshots is 24 hours, if the snapshot lag at least explain this website is not very good. We should also take a look at this site included, if included is stable, indicating that the site update is persistent, spiders are generally more stable renewal of love. To see you and then keywords site ranking, the ranking is also very important, ranking at least explain this website has a certain flow, but also look at the website domain name registration time,. Finally, the total number of 0 party want to take a look at the website chain best can be maintained at about 30, the maximum not more than 50, if the website of the other side chain too much, then transfer to the weight of your web site also does not have what meaning.