what is the use of dictionary in python..... because there are lists also available in python so why don't we use them instead of dictionary.

Answer 1

This comes down to query speed and the concept of "BigO" which will be visited in later lessons. In short, querying dictionaries in Python is much faster than querying lists.

http://stackoverflow.com/questions/513882/python-list-vs-dict-for-look-up-table