A Sensor is a small piece of code that instuments the monitored applications at certain points to extract the relevant data. For example, a Sensor can transport tagging information from one host to another when a web service call is executed. The AppMon installation includes a set of built-in Knowledge Sensor Packs for a wide set of application servers and frameworks. These Knowledge Sensor Packs are maintained by AppMon. You can activate/deactivate them as needed.