Clipboard and its copy, cut and paste is the essential function of any operating system. When you’re editing a text in OS X, you use Command-C to copy or Command-X to cut a piece of text to the clipboard, and Command-V to paste that text back.
Command-V will always paste back the last copy/cut text. What if you want to grab two separate pieces of text and paste them into one location? Turns out that in OS X there are Kill and Yank editing commands that can act as secondary clipboard for copy-and-paste.
Kill and Yank are editing commands thus are only available when you’re editing text in application such as TextEdit. You can not perform these commands on non-editing text such as on a web page.
When you Kill a text, that piece of text is removed from the editor and placed into a secondary buffer area similar to clipboard. You can then Yank (paste) the text back to the editor. These are similar operations to Cut and Paste via the clipboard.
To Kill a text, select the text and hit Control-K. If there is no text selection, Control-K will kill the text from cursor onwards to the end of the paragraph. To Yank (paste) the text back out, hit Control-Y.
You will notice that Kill and Yank operate independently from the clipboard. Try enter Command-V to confirm.