diff --git a/README.md b/README.md
index 2f8be46..08b8793 100644
--- a/README.md
+++ b/README.md
@@ -1,16 +1,14 @@
-IRext Encoding and Decoding Core Library
+## IRext Encoding and Decoding Core Library
 
-	This project contains IRext core encode algorithm and decode algorithm.
+  This project contains IRext core encode algorithm and decode algorithm.
 
-Summary
+#### Summary
 
-	IR code is base on 38000Hz or 56000Hz carrier waves, it is identified by the time interval of carrier waves.
+  IR code is base on 38000Hz or 56000Hz carrier waves, it is identified by the time interval of carrier waves.
 
-	Identical control signal is defined by pairs of physical high and low levels, eg. the NEC encoding bits as below :
+  Identical control signal is defined by pairs of physical high and low levels.
 
-(image of IR code)
-
-	The lead code is identified by the 9000us time interval with carrier waves and 4500us interval without carrier waves. The logic 0 is identified by 500us time interval with carrier waves and 500us interval without carrier waves. The logic 1 is identified by 500us time interval with carrier waves and 1500us interval without carrier waves, so are the other types of encoding.
+  The lead code is identified by the 9000us time interval with carrier waves and 4500us interval without carrier waves. The logic 0 is identified by 500us time interval with carrier waves and 500us interval without carrier waves. The logic 1 is identified by 500us time interval with carrier waves and 1500us interval without carrier waves, so are the other types of encoding.
 
 Following are some specifications:
 
@@ -30,26 +28,26 @@ Following are some specifications:
 - Command code: The receiver receives IR code as commands from emitter, and then adjusts status of itself, eg. control code of TV, DVD.
 - Status code: The receiver receives IR code as status, and applies itself to this status, eg. control code of air conditioner.
 
-Encoder
+#### Encoder
 
-	The encoder composes compressed remote control IR binaries from plain text in XML format. Different kind of remote control code are differently composed.
+  The encoder composes compressed remote control IR binaries from plain text in XML format. Different kind of remote control code are differently composed.
 
-Command code
+__Command code__
 
-	Command code is composed by 2 parts : protocol segment and control segment which are stored in 2 parts. When encode, the remote control key code would be calculated and translated according to protocol definition and merge separate segments into a complete control frame.
+  Command code is composed by 2 parts : protocol segment and control segment which are stored in 2 parts. When encode, the remote control key code would be calculated and translated according to protocol definition and merge separate segments into a complete control frame.
 
-Status code
+__Status code__
 
-	Status code is defined by various kinds of tags, indication each essential part in one status control frame. It is especially used for air conditioners.
+  Status code is defined by various kinds of tags, indication each essential part in one status control frame. It is especially used for air conditioners.
 
-Decoder
+#### Decoder
 
-	The decoder decodes IR remote control binaries into IR control frame which is composed by time series illustrated above.
+  The decoder decodes IR remote control binaries into IR control frame which is composed by time series illustrated above.
 
-	The input of decode algorithm is the IR remote control binary file or its content in bytes, the keycode and category id get from indexing API. 
+  The input of decode algorithm is the IR remote control binary file or its content in bytes, the keycode and category id get from indexing API. 
 
-	The output of the algorithm is the time series, which can be sent to IR emit driver function to send IR control waves to the family equipment.
+  The output of the algorithm is the time series, which can be sent to IR emit driver function to send IR control waves to the family equipment.
 
-	Please refer to https://irext.net/doc/ for details.
+  Please refer to https://irext.net/doc/ for details.