To monitor or monitoring generally means to be aware of the state of a system. Below are a couple of specific examples:

• to observe a situation for any changes which may occur over time, using a monitor or measuring device of some sort:
  • Baby monitor, medical monitor, Heart rate monitor
  • Biomonitoring
  • Condition monitoring
  • Network monitoring
  • Election monitoring
• to observe the behaviour or communications of individuals or groups (see surveillance)

Monitoring