Dictionary in C#

• Dictionary is generic collection and includes System.Collections.Generic namespace.
• This is collection of Key and value pair and key must be a unique.
• In the dictionary, you cannot be including duplicate key. 
• In the dictionary, duplicate key given run time error.

NOTE:

1. It returns error if we try to find a key which does not exist.
2.  It is faster than a hash table because there is no boxing and unboxing.
3. Dictionary is a generic type which means we can use it with any data type.