diff --git a/Custom-Sensor.md b/Custom-Sensor.md
index d575f32..368db1c 100644
--- a/Custom-Sensor.md
+++ b/Custom-Sensor.md
@@ -1,5 +1,10 @@
 # Custom Sensor
 
+CraftBeerPi destiguises between Active and Passive Sensors
+
+* Active Sensors: Has to handle it's own loop and push data to CraftBeerPi
+* Passive Sensors: Are executed every 5 seconds by CraftBeerPi to pull new data
+
 ## Active Sensor
 
 ```