Function: kill-ring-save

Save the region as if killed, but don't kill it.
In Transient Mark mode, deactivate the mark.
If `interprogram-cut-function' is non-nil, also save the text for a window
system cut and paste.

If you want to append the killed line to the last killed text,
use C-M-w before M-w.

This command is similar to `copy-region-as-kill', except that it gives
visual feedback indicating the extent of the region being copied.