Link type
 

Reference links: the lead web cited cited the contents of the website. In the academic website, reference links similar traditional citation links.
Put up links: link and the links between web page does not exist sure coherence, such as some sites in the network application often some of the website to give a press link.
Advertising links: commercial benefits for the target of the link, this type of link directly by search engines as no reference value of the link.