Parameters are deprecated since Joomla! 1.6 . Configuration options can now be defined using form fields.
Parameters are a mechanism in Joomla! 1.5 that enables administrators to configure Joomla! itself or its extensions. Parameters allow many aspects of the behaviour of Joomla or its extensions to be customised without requiring the user to know how to change the underlying code.
It is possible to add support for additional parameter types beyond the standard parameter types. This page lists resources for adding custom parameter types and gives a list of example custom parameter types.
If you are a developer and you have created an interesting or useful custom parameter type, then please feel free to add it this list.