Everyone tells you to go to the doctor regularly, but why should you? What are the benefits? My parents would say that you should go to the doctor to catch signs of things that you do not necessarily pay attention to, or notice, by yourself. This could be things like cholesterol levels, blood pressure, and skin cancer. I also like to use doctor visits as a time to think about and talk about changes that I have noticed in my body. For example, if I have had an upset stomach frequently.
These examples work as good comparisons of the two separate types of monitoring that software often needs. The first type is metrics and the second is logs. Metrics, in this case, are number measurements. Traditionally, metrics focused on performance numbers, like the percentage of disk space used, or the number of packets received, or the CPU load. These days, they can be used to represent just about anything that can be defined as a numerical value. They can come from any piece of software...