You can see the current value of a variable, any variable, by using
the describe-variable function, which is usually invoked by
typing C-h v. If you type C-h v and then kill-ring
(followed by RET) when prompted, you will see what is in your
current kill ring—this may be quite a lot! Conversely, if you have
been doing nothing this Emacs session except read this document, you
may have nothing in it. Also, you will see the documentation for
kill-ring:
Documentation: List of killed text sequences. Since the kill ring is supposed to interact nicely with cut-and-paste facilities offered by window systems, use of this variable should
interact nicely with `interprogram-cut-function' and `interprogram-paste-function'. The functions `kill-new', `kill-append', and `current-kill' are supposed to implement this interaction; you may want to use them instead of manipulating the kill ring directly.
The kill ring is defined by a defvar in the following way:
(defvar kill-ring nil "List of killed text sequences. …")
In this variable definition, the variable is given an initial value of
nil, which makes sense, since if you have saved nothing, you want
nothing back if you give a yank command. The documentation
string is written just like the documentation string of a defun.
As with the documentation string of the defun, the first line of
the documentation should be a complete sentence, since some commands,
like apropos, print only the first line of documentation.
Succeeding lines should not be indented; otherwise they look odd when
you use C-h v (describe-variable).