diff --git a/docs/source/api_introduction.rst b/docs/source/api_introduction.rst
new file mode 100644
index 00000000..986ae329
--- /dev/null
+++ b/docs/source/api_introduction.rst
@@ -0,0 +1,17 @@
+API Introduction
+****************
+
+There are a few key classes for communication with the Rest API of HomematicIP.
+
+| **Home:** is the most important object as it has the "overview" of the installation
+| **Group:** a group of devices for a specific need. E.g. Heating group, security group, ...
+| **MetaGroup:** a collection of groups. In the HomematicIP App this is called a "Room"
+| **Device:** a hardware device e.g. shutter contact, heating thermostat, alarm siren, ...
+| **FunctionChannel:** a channel of a device. For example DoorLockChannel for DoorLockDrive or **DimmerChannel**. A device has multiple channels - depending on its functions.
+
+| For example:
+| The device HmIP-DLD is represented by the class **DoorLockDrive** (or AsyncDoorLockDrive). The device has multiple channels. 
+| The base channel holds informations about the device and has the index 0.
+| The device has also a channel called **DoorLockChannel** which contains the functions "set_lock_state" and "async_set_lock_state". These are functions to set the lock state of that device.
+
+If you have dimmer with multiple I/Os, there are multiple channels. For each I/O a unique channel. 
\ No newline at end of file
diff --git a/docs/source/index.rst b/docs/source/index.rst
index 3afbb6da..d390474d 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -12,7 +12,7 @@ done via reverse engineering. Use at your own risk.
 
 .. toctree::
    :maxdepth: 2
-   :caption: Introduction
+   :caption: Getting started
 
    gettingstarted
    
@@ -20,6 +20,7 @@ done via reverse engineering. Use at your own risk.
    :maxdepth: 4
    :caption: API Documentation
 
+   api_introduction
    modules
 
 Indices and tables
diff --git a/src/homematicip/base/functionalChannels.py b/src/homematicip/base/functionalChannels.py
index b61a56a7..47aa1de8 100644
--- a/src/homematicip/base/functionalChannels.py
+++ b/src/homematicip/base/functionalChannels.py
@@ -1,5 +1,5 @@
-from typing import Iterable
 import json
+from typing import Iterable
 
 from homematicip.base.enums import *
 from homematicip.base.HomeMaticIPObject import HomeMaticIPObject