1. A method of summarizing a first unit of text data with relation to an existing document collection, comprising: computing a term weight that is representative of the relevance of a term to a second unit of text data with relation to the existing document collection; performing one of a domain driven text summarization, an example type query driven text summarization, and a term type query driven text summarization on a selected document; recomposing a vector representation of at least one of the first and second units of text data in a predetermined multidimensional subspace representing the existing document collection when performing domain driven text summarization or example type query driven text summarization, the recomposing being performed by projecting the vector representation back into an original term space of the existing document collection; computing a relationship of the term to the terms in a query using a term-term matrix associated with the original term space when performing term type query driven text summarization; comparing the computed term weight to a predetermined threshold; and returning a relevant term based at least in part on a result of the comparison.