Declaring

Initializing

Added in .NET 4.6
There is now another way which is a more readable format

public Dictionary <string, string> MyDictionary = new Dictionary<string, string>() 
{ 
   {"Russell", "London"} 
   {"Steven","New York"} 
} 

instead of

public Dictionary <string, string> MyDictionary = new Dictionary<string, string>() 
{ 
   ["Russell"] = "London" 
   ["Steven"] = "New York" 
}