Sometimes end users interchange the terms : C2 auditing and Traces.
They server different purposes.

c2 auditing records all attempts (successfull and failed) on objects and statements. Typically a SQL Server DBA will use a c2 audit to monitor security compliance .

A trace will will monitor an event or a series of events. Events can be any source producing a trace events. Examples are deadlocks and DTC transactions, SQL Server Backups.Read BOL for a comprehensive list of events

To view if c2 auditing is turned on use:

--To view if c2 auditing is turned on use:
EXEC sp_configure 'c2 audit mode'
--To view if traces including user defined ones are running on SQL server 2005 use:
SELECT * FROM sys.fn_trace_getinfo(0) ;

Author: Jack Vamvas (http://www.sqlserver-dba.com)