Hashtables (also called dictionaries, maps, or associative arrays) are data structures that allow you to store named items. They are similar to Python's dictionaries. For example:
Boo's hash class is defined in Boo.Lang.Hash, which is a subclass of the standard System.Collections.Hashtable class. See that page for more documentation about the methods and properties that boo's hashtable inherits.
If you haven't already, you should learn about Lists And Arrays also.
Here is a sample of things you can do with a dictionary:
See also Lists And Arrays.