Abstract: A system for personalization of a search engine for a network includes a least one search account. A first data structure stores index data for words each having a number of resources less than a first number. A second data structure stores index data for words each having a number of resources greater than the first number and less than a second number. The second data structure can be personalized for the search account. A third data structure stores index data for words each having a number of resources greater than the second number. The third data structure can be personalized for search account. At least one index includes the first data structure, the second data structure and the third data structure where when the search engine responds to a query from a user of a search account, the search engine uses an index corresponding to the search account.