Some messages for built-in functions are off by default, and must explicitly be switched on using On.
On[General::name] switches on all messages derived from General::name.
When tracing is switched on, each evaluation of a symbol, on its own or as a function, is printed, together with the result.
Note that the tracing information is printed when a function returns. As a result, traces of recursive functions appear in the opposite order from their calls.
EXAMPLES
Basic Examples 
