what does logging mean in computer terms code example

Example: how do you logging

Log4j

How do you use Log4J in your framework?
printing/logging the important events 
of the application/test run.
in my project I did logging using the log4j 
library. I added the library dependency
into pom.xml. For logging we create an 
object from Logger Interface and LogManager 
class using getLogger method and
passing the class name in it;  

private static Logger log = LogManager.getLogger(LogDemo.class.getName());
static Logger log = Logger.getLogger(log4jExample.class.getName());

We create it by passing the name of the 
current class. Then we can use this
object to do our logging.
log.info
log.debug
log.fatal
log.error

The Logger object is responsible for
capturing logging information and they
are stored in a namespace hierarchy.