Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. VCL (Visual Component Library) is a visual component-based object-oriented framework for developing Microsoft Windows applications. It was developed by Borland for use in, and tightly integrated with, its Delphi and C++ Builder RAD tools (now owned by CodeGear, division of Embarcadero Technologies). It is written in Object Pascal. A cross-platform equivalent of the VCL, called CLX, was later developed for use in Delphi, C++ Builder and Kylix. It was however abandoned in favor of the VCL. VCL forms a class hierarchy with a common ancestor, the TComponent class (which inherits from TObject, the root class in Delphi Object Pascal). This is a common approach shared by the Java programming language, Smalltalk, C Sharp (programming language) and many other object-oriented programming languages.