And in Emacs ctrl+k means kill the line or selection (adds it to the kill ring) and ctrl+y yanks a value from the kill ring. Meta+y cycles to the next item in the ring. Meta is usually escape, unless you're using the computer of someone with a key called meta

This comes from being earlier than MS-DOS, so it couldn't copy someone else's work (why did it take so long for DOS and windows to come up with the innovation of a copy history. It came after the windows key