diff --git a/README.md b/README.md
index 7a1e453..3754998 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,40 @@
 
 -   multiple data inputs: hwmon, d-bus, direct driver access
 
+## dbus interfaces
+
+A typical dbus-sensors object support the following dbus interfaces:
+
+```
+Path        /xyz/openbmc_project/sensors/<type>/<sensor_name>
+
+Interfaces  xyz.openbmc_project.Sensor.Value
+            xyz.openbmc_project.Sensor.Threshold.Critical
+            xyz.openbmc_project.Sensor.Threshold.Warning
+            xyz.openbmc_project.State.Decorator.Availability
+            xyz.openbmc_project.State.Decorator.OperationalStatus
+            xyz.openbmc_project.Association.Definitions
+
+```
+Sensor interfaces collection are described [here](https://github.com/openbmc/phosphor-dbus-interfaces/tree/master/yaml/xyz/openbmc_project/Sensor).
+
+Consumer examples of these interfaces are [Redfish](https://github.com/openbmc/bmcweb/blob/master/redfish-core/lib/sensors.hpp), [Phosphor-Pid-Control](https://github.com/openbmc/phosphor-pid-control), [IPMI SDR](https://github.com/openbmc/phosphor-host-ipmid/blob/master/dbus-sdr/sensorcommands.cpp).
+## Reactor
+dbus-sensor daemons are [reactors](https://github.com/openbmc/entity-manager)
+that dynamically create and update sensors configuration when
+system configuration gets updated.
+
+Using asio timers and async calls, dbus-sensor daemons read sensor values and check thresholds periodically.
+PropertiesChanged signals will be broadcasted for other services to consume when
+value or threshold status change.
+OperationStatus is set to false if the sensor is determined to be faulty.
+
+A simple sensor example can be found [here](https://github.com/openbmc/entity-manager/blob/master/docs/my_first_sensors.md).
+
+## configuration
+Sensor devices are described using Exposes records in configuration file.
+Name and Type fields are required. Different sensor types have different fields.
+Refer to entity manager [schema](https://github.com/openbmc/entity-manager/blob/master/schemas/legacy.json) for complete list.
 ## sensor documentation
 
 -   [ExternalSensor](https://github.com/openbmc/docs/blob/master/designs/external-sensor.md)