Apriori Algorithm is to find association rules and frequent item sets (also closed and maximal as well as generators). It is used for Frequent Pattern Mining.

References:

  1. http://lsirwww.epfl.ch/courses/dis/2005ws/exercises/apriori/www/
  2. http://www2.cs.uregina.ca/~dbd/cs831/notes/itemsets/itemset_prog1.html