20. The method of claim 19 , further comprising: receiving a query containing a keyword; matching a term in the index or in the first chronological segment with the keyword in the query; and returning, as a search result, one or more documents or document segments associated with the matched term.
19. A computer-assisted method for indexing and searching information in document segments, comprising: receiving a plurality of documents, wherein each of the documents is in the form of a communication thread, comprising multiple segments, wherein at least two of the segments are created by different persons, wherein the multiple segments are chronologically organized based on the time each segment is added to the document; for each of the plurality of documents, identifying the first chronological segment in the document, wherein the first chronological segment contains the content that is most recently added to the document by a specific person in the communication thread, wherein the content of the first chronological segment is a response to the content of a different segment in the document created by a different person at a different time; dividing the document into a first part and a second part, wherein the first part comprises the first chronological segment, wherein the second part comprises the portion of the document that is not the first chronological segment; and building a search index based on the terms in the first part in one or more of the plurality of documents.