Part of the job consisted of monitoring a collection of fairly critical backed processes, to see how well they were performing and whether or not they were going wrong.
We developers spend a lot of time and energy adding logging to our application in order to prove that it's working okay and to figure out what went wrong when an exception occurs. These log files are often used to tell us how well, or badly, our application is performing on a daily basis.
I'm ignoring other techniques such as adding probes to your application by whatever method you choose, such as HTTP or JMX. These provide immediate information on your application rather than the second level monitoring under discussion here.
There are at least three ways of monitoring log files: