FreeSpan is a sequential-pattern-mining algorithm based on frequent-pattern projection, using a divide-and-conquer strategy. Instead of generating and testing candidate sequences, it recursively uses the current set of frequent items to project the sequence database into a set of smaller projected databases, then mines sub-sequence fragments within each projection. This confines each subsequent test to a smaller projected database that matches the pattern being examined, dividing both the data and the set of patterns under consideration. Advantage: it reduces the overhead of generating candidate sequences. Disadvantage: it may generate many projected databases, which can become computationally expensive.