A method of determining a relation between search queries and a system for executing the method are provided. A method of determining a relation between search queries, comprises: maintaining a database including a search session and search queries received from a user terminal during the search session; determining numbers of search sessions where first and second search queries are received during a predetermined time interval; calculating conditional probability based on the determined numbers of search sessions; calculating correlation by using a total number of search sessions and said numbers of search sessions; and determining a relation between said search queries based on said calculated conditional probability and said calculated correlation.