1. A system to provide a search result, the system comprising: a search term reception unit to receive a search term; a processor to extract information corresponding to at least one of a first personal network associated with the search term and a second personal network different than the first personal network; a search result providing unit to provide a document associated with at least one of the first personal network and the second personal network as a search result of the search term; and a neighbor information extraction unit to extract information corresponding to at least one neighbor having interests corresponding to interests of a user, the information corresponding to the at least one neighbor being based, at least in part, on a profile of the user, the profile being configured using keywords in a document prepared by the user, and the search term being received from the user, the keywords being time-variable and corresponding to keywords having the highest frequency of occurrence in the document.
2. The system of claim 1 , further comprising: a personal network setting unit to set, as a personal network of the user, at least one of communities joined by the user, the at least one neighbor, and communities joined by the at least one neighbor.