Single Channel Sensors return only one value and are placed in the "\Custom Sensors\EXE" folder
of your PRTG Network Monitor installation.
Multi Channel Sensors return a XML result that can consist out of one or more channels. These sensors are placed in the "\Custom Sensors\EXEXML" folder of your PRTG Network Monitor installation
Notifications are used to send alerts to the user whenever PRTG discovers a defined state, such as slow or failing sensors, or when thresholds are reached.
Notifiers will give you a visible notification on your Windows desktop or mobile phone, when a sensors treshold is reached.
Various tools to make your life a bit easier.
Miscellaneous tools, not related to your PRTG Network Monitor installation.