How Does Windows Clipboard Work?

Accessing the Clipboard

To obtain access to the clipboard, most applications will allow you to use the Ctrl-C and Ctrl-V shortcut key combinations. When you have something selected in an application, such as an image or a piece of text, you can hold down the Control key (Ctrl) and press the C key. This will cause whatever you have selected to be placed on the clipboard. This is known as the "copy" command. When you have the cursor located at a place where you want to put what you just placed on the clipboard, you can hold down the Control key again and this time press the V key. This will place an exact copy of whatever you placed on the clipboard at the location of the cursor. This is known as the "paste" command. You can also usually access these commands from the menu at the top of the application under the "Edit" option, and in many cases you can access these commands by right-clicking on your selection and choosing either "copy" or "paste" from the shortcut menu that appears.

Behind the Scenes

When you make these selections, what happens behind the scenes is that the Windows operating system will keep track of what you have done. There is an object that exists in the operating system, outside of all the applications that you are running that is actually called the clipboard object. The operating system exposes parts of that object to all applications that want it. Then, when the application senses the key combination that requests a copy, the application sends the information that was to be copied to the operating system. The operating system takes a copy of that information and stores it in a location in memory that is only available to the operating system. When an application wants to paste from the clipboard, the application asks the operating system to give it whatever is currently located in the clipboard location.

The Cut Command

An additional command that accesses the clipboard object is the "cut" command. This can often be accessed with the "Ctrl-X" key combination. However, this option is a bit more limited because when you attempt to "cut" something from a location, you will attempt first to delete what is selected. This is not always an option. For example, when you are viewing a web page in your browser, you cannot select some text and delete it. It does work in many other applications, such as word processing programs. After the delete option, the cut command is identical to the copy command--it places the selected text on the clipboard object where it is then available to other applications via the paste command.

Overwrite

In most situations, there is one clipboard object and it can only store one thing at a time. There are exceptions to this rule, notably inside various applications like Microsoft Office. This means that when you copy paragraph one from a text document to the clipboard, then copy an image from a webpage to the clipboard, the paragraph disappears--copy does not ask you if you want to replace the contents, it will automatically replace it whenever you copy something onto the clipboard.