Edited sentence: In general, Swing users can extend the framework by extending existing (framework) classes and/or providing alternative implementations of core components.On April 2 1997, Sun Microsystems and Netscape Communications Corporation announced their intention to incorporate IFC with other technologies to form the Java Foundation Classes.Originally distributed as a separately downloadable library, Swing has been included as part of the Java Standard Edition since release 1.2.Swing introduced a mechanism that allowed the look and feel of every component in an application to be altered without making substantial changes to the application code.Swing is a highly partitioned architecture, which allows for the "plugging" of various custom implementations of specified framework interfaces:  Users can provide their own custom implementation(s) of these components to override the default implementations.The Internet Foundation Classes (IFC) were a graphics library for Java originally developed by Netscape Communications Corporation and first released on December 16 1996.The Swing classes and components are contained in the  package hierarchy.The introduction of support for a pluggable look and feel allows Swing components to emulate the appearance of native components while still retaining the benefits of platform independence.This feature also makes it easy to make an application written in Swing look very different from native programs if desired