diff --git a/README.md b/README.md
index 7891d0f..0abde99 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,10 @@
 - [JSON](#JSON)
 - [Third Party Library](#Third-Party-Library)
 - [GCD](#GCD)
+    - [DispatchQueue](#DispatchQueue)
+    - [DispatchGroup](#DispatchGroup)
+    - [DispatchWorkItem](#DispatchWorkItem)
+    - [Address Sanitizer](#Address-Sanitizer)
 - [Useful Stuff](#Useful-Stuff)
     - [Show Preview in UIKit(Build UI with Code Base)](#show-preview-in-uikitbuild-ui-with-code-base-----)
     - [Write README.md](#write-readmemd)
@@ -187,6 +191,19 @@ This extension makes JSON more structable
 ## GCD
 GCD(Grand Central Dispatch) is a low-level API for managing concurrent operations. It can help you improve your app’s responsiveness by deferring computationally expensive tasks to the background.
 
+### DispatchQueue
+
+#### main
+
+#### global()
+
+### DispatchGroup
+
+### DispatchWorkItem
+
+### Address Sanitizer
+Address Sanitizer is a good way to find the [Readers and Writers problem](#https://en.wikipedia.org/wiki/Readers%E2%80%93writers_problem) in your application.
+
 ## Third Party Library
 [This github](https://github.com/vsouza/awesome-ios) contains all the popular libraries in Swift:+1: