eintr: fill-column Example
‘fill-column’, an Example Variable
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The variable ‘fill-column’ illustrates a symbol with a value attached to
it: in every GNU Emacs buffer, this symbol is set to some value, usually
72 or 70, but sometimes to some other value. To find the value of this
symbol, evaluate it by itself. If you are reading this in Info inside
of GNU Emacs, you can do this by putting the cursor after the symbol and
typing ‘C-x C-e’:
fill-column
After I typed ‘C-x C-e’, Emacs printed the number 72 in my echo area.
This is the value for which ‘fill-column’ is set for me as I write this.
It may be different for you in your Info buffer. Notice that the value
returned as a variable is printed in exactly the same way as the value
returned by a function carrying out its instructions. From the point of
view of the Lisp interpreter, a value returned is a value returned.
What kind of expression it came from ceases to matter once the value is
known.
A symbol can have any value attached to it or, to use the jargon, we
can “bind” the variable to a value: to a number, such as 72; to a
string, ‘"such as this"’; to a list, such as ‘(spruce pine oak)’; we can
even bind a variable to a function definition.
A symbol can be bound to a value in several ways. 
Setting the
Value of a Variable set & setq, for information about one way to do
this.
Info Catalog
eintr: Variables
eintr: Void Function