15. The storage medium of claim 14 , wherein the instructions to store the one or more extracted words in the word balanced tree further comprises: storing the one or more extracted words and associated digital documents in one or more pages in a page memory system, wherein the one or more pages are maintained using a page table including, for each of the one or more pages, associated page identifiers, a page status, and a number of allocated word blocks in each of the one or more pages.
14. The storage medium of claim 13 , wherein the instructions to store the one or more extracted words in the word balanced tree further comprises: counting an occurrence of the word associated with the node of the word balanced tree in the set of digital documents of r one of the plurality of the nodes; determining whether the occurrence of the word associated with the node is greater than a predetermined occurrence threshold; restarting counting an occurrence of the word in another set of digital documents if the determined occurrence of the word associated with the node is greater than the predetermined occurrence threshold; and continuing the counting of the occurrence of the word in the set of digital documents until a number of occurrences of the word in the set of digital documents becomes equal to the predetermined occurrence threshold.