1. A method for linking documents, comprising a computer performing the steps of: obtaining a set of documents, wherein documents in the set of documents are not interlinked with other documents via one or more hyperlinks; forming a plurality of clusters from the set of documents, each cluster comprising one or more documents; building a cluster page for each cluster to represent the documents in the cluster; and building links based on analysis of the contents of the clusters and the documents; wherein, when a similarity of a topic of a first document of the set of documents to a second document of the set of documents is greater than a threshold, a link is built from the first document to the second document, the similarity being a cosine function of an angle between a topic vector of the first document and a document vector of the second document; wherein said step of building links comprises one or more of the following steps: building the link between the cluster pages; building the link from the cluster page to the document; building a link from the document to the cluster page; and building the link between the documents; wherein, when the number of documents commonly owned by a first cluster and a second cluster is greater than or equal to a threshold, build the links between the cluster page of the first cluster and the cluster page of the second cluster; and wherein, when the proportion of the number of commonly owned documents in the first cluster is greater than that in the second cluster, generate a link from the cluster page of the second cluster to the cluster page of the first cluster, otherwise generate a link from the cluster page of the first cluster to the cluster page of the second cluster.