In this chapter, you learned the basic definition of the dictionary, or associative array, data structure. You learned how to initialize dictionaries, and we examined the hash table data structure upon which most concrete dictionary implementations are based. We discussed the various common operations found in dictionaries, including their operational costs. Following this, we examined a case study where dictionaries would be very beneficial. Finally, we looked at two varying implementations of dictionaries, including the hash table based dictionary and the search tree based dictionary.