A clipboard viewer is a window that displays the current content of the clipboard. The clipboard viewer window is a convenience for the user and does not affect the data-transaction functions of the clipboard.
Typically, a clipboard viewer window can display at least the three most common formats: CF_TEXT, CF_BITMAP, and CF_METAFILEPICT. If a window does not make data available in any of these three formats, it should provide data in a display format or use the owner-display format.
A clipboard viewer chain is the linking together of two or more entities so that they are dependent upon one another for operation. This interdependency (chain) allows all running clipboard viewer applications to receive the messages sent to the current clipboard.