A method of generating popularity rankings of search terms includes generating a ranking value table including ranking values corresponding to rankings of search terms, determining first ranking values corresponding to previous rankings of a plurality of search terms and second ranking values corresponding to current rankings of the plurality of search terms by using the ranking value table, and obtaining difference values based on differences between the first ranking values and the second ranking values of the plurality of search terms, respectively, and determining popularity rankings of the plurality of search terms by using the difference values.