1. A method, performed by one or more server devices, the method comprising: receiving, by a processor of the one or more server devices, a first document; identifying, by a processor of the one or more server devices, a plurality of second documents that each include a link pointing to the first document; determining, by a processor of the one or more server devices, a second document of the plurality of second documents that has been used to access the first document more than any other second document of the plurality of second documents; extracting, by a processor of the one or more server devices, concepts associated with the determined second document; and associating, by a processor of the one or more server devices, the extracted concepts with the first document, at least one extracted concept, of the extracted concepts, being associated with anchor text in the determined second document.