The usual way to reference a variable is to write the symbol which names it. See Symbol Forms.
Occasionally, you may want to reference a variable which is only
determined at run time. In that case, you cannot specify the variable
name in the text of the program. You can use the
function to extract the value.
This function returns the value stored in symbol’s value cell.
This is where the variable’s current (dynamic) value is stored. If
the variable has no local binding, this is simply its global value.
If the variable is void, a
void-variable error is signaled.
If the variable is lexically bound, the value reported by
symbol-value is not necessarily the same as the variable’s
lexical value, which is determined by the lexical environment rather
than the symbol’s value cell. See Variable Scoping.
(setq abracadabra 5) ⇒ 5
(setq foo 9) ⇒ 9
;; Here the symbol
abracadabra;; is the symbol whose value is examined. (let ((abracadabra 'foo)) (symbol-value 'abracadabra)) ⇒ foo
;; Here, the value of
abracadabra, ;; which is
foo, ;; is the symbol whose value is examined. (let ((abracadabra 'foo)) (symbol-value abracadabra)) ⇒ 9
(symbol-value 'abracadabra) ⇒ 5