This video explains the need for using hashmap and how it improves the frequent operations time complexity.I have compared all the simple data structures with hashmap based on search as our frequent operation.I have shown that if searching is frequently used then hashmap helps us achieve a constant time for searching.It is also very space efficient which I have shown by comparing it with array.I have also explained direct address table or DAT.I have shown the advantages and limitations of a direct address table and how hashmap is one of the most efficient data structure if we talk about insertion,searching and deletion with searching based on key being the most frequent operation.