Using the core parameter types

From Joomla! Documentation

Parameters are one way in which data may be stored for a Joomla! Extension. Each parameter consists of two parts: a simple text string of the form {NAME} = {VALUE}, in which the parameter value is recorded (usually concatenated into a single string with other parameter values, and stored in a table field); and a form field in the Extension backend, which allows a user to enter the parameter value, and which is defined by an xml <param> element.

Joomla! defines 21 different core parameter types, each of which gives a predefined behaviour and appearance in the back-end. This makes it very easy for developers to implement a range of different form data entry types (text boxes, radio buttons, calendar selectors, etc) with a minimum of effort. This behaviour and appearance is determined by the type attribute of the <param> element. See Standard parameter types for a complete list and details of each type.