(Or "cut and paste", after the paper, scissors and glue method of document production) The system supported by most document editing applications (e.g. text editors) and most operating systems that allows you to select a part of the document and then save it in a temporary buffer (known variously as the "clipboard", "cut buffer", "kill ring"). A "copy" leaves the document unchanged whereas a "cut" deletes the selected part.
A "paste" inserts the data from the clipboard at the current position in the document (usually replacing any currently selected data). This may be done more than once, in more than one position and in different documents.
More sophisticated operating systems support copy and paste of different data types between different applications, possibly with automatic format conversion, e.g from rich text to plain ASCII.
GNU Emacs uses the terms "kill" instead of "cut" and "yank" instead of "paste" and data is stored in the "kill ring".
[Origin? Macintosh? Xerox?]