Used in conjuction with [curl->set] to direct curl to display a lot of verbose information about its operations.

Set the parameter to 1 to get the library to display a lot of verbose information about its operations. 

Very useful for debugging. The verbose information will be sent to stderr, or the stream set with CURLOPT_STDERR.

You hardly ever want this set in production use, you will almost always want this when you debug/report problems. Another neat option for debugging is the CURLOPT_DEBUGFUNCTION.