a file that is written to with system or program information, and instead of writing the information in readable text, the information is formated in such a why that a program is needed to interpret it
                                                            
                                                     
                        
                                                
                        
                        
                            a file with data that is not human readable
                                                            
                                                     
                        
                                                
                        
                        
                            a log file format used by tools based on libpcap libraries like Ethereal , tcpdump or Snort , to log and analyze network traffic