diff --git a/README.md b/README.md
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+++ b/README.md
@@ -12,3 +12,145 @@ Distributes users onto different classes, each had its own permissions
 
 ## Libraries
 editormd
+
+## Cavern API Quick Start
+To get data from Cavern, a recommended way is to use the **Cavern API**.
+
+Following are 2 commonly used api endpoints to create a viewer for the Cavern website.
+
+- [Posts](#Posts)
+- [User Profile](#User-Profile)
+
+To see full documentation, please visit [reference](reference.md).
+
+### Posts
+#### Posts list
+In order to get posts, the following endpoint is used
+```
+/ajax/posts.php
+```
+The reponse of the api call contains 
+- fetch series(```fetch```)
+- number of posts(```page_limit```)
+- current page(```page```)
+- number of all posts(```all_posts_count```)
+- posts list(```posts```)
+
+and each post inside posts list contains
+- author's username(```author```)
+- author's displayed name(or nickname)(```name```)
+- the PID of the post(```pid```)
+- the title of the post(```title```)
+- the time when the post is sent(```time```)
+- the number of likes the post received(```likes_count```)
+- the number of comments about the post(```comments_count```)
+- whether the current user has liked it(*note: if it isn't logged, the result will be false*)(```islike```)
+
+```json
+{
+    "fetch":1570115846126,
+    "page_limit":1,
+    "page":3,
+    "all_posts_count":200,
+    "posts":
+    [
+        {
+            "author":"ExampleAuthor", 
+            "name":"AuthorName",
+            "pid":300,
+            "title":"ExampleTitle",
+            "time":"2019-08-29 13:00:00",
+            "likes_count":"1",
+            "comments_count":"3",
+            "islike":false
+            
+        }
+    ]
+}
+```
+To change the number of posts you want to receive or current page, you can specify the  ```limit``` and ```page``` arguments.
+
+```
+/ajax/posts.php?limit={number of posts}&&page={page number}
+```
+
+#### Post Content of a Specific PID
+To get an post's content, you must access it with its PID.
+```
+/ajax/posts.php?pid={PID}
+```
+The response contains 
+- fetch series(```fetch```)
+- post content(```post```)
+
+The body of post contains
+- author's username(```author```)
+- author's diaplyed name(or nickname)(```name```)
+- the title of the post(```title```)
+- the content of the post(```content```)
+- the time when the post is sent(```time```)
+- the number of likes the post received(```likes_count```)
+- the number of comments about the post(```comments_count```)
+- whether the current user has liked it(*note: if it isn't logged in, the result will be false*)(```islike```)
+
+```json
+{
+    "fetch":1570117194098,
+    "post":
+    {
+        "author":"ExampleAuthor",
+        "name":"ExampleAuthorName",
+        "title":"ExampleTitle",
+        "content":"ExampleContent",
+        "time":"2019-06-01 12:00:00",
+        "likes_count":"0",
+        "comments_count":"10",
+        "islike":false
+    }
+}
+```
+
+### User Profile
+
+#### User's level
+In Cavern API, we use different level number to represent the ability to access resources and functionality. 
+The following table is the level numbers and its permissions.
+
+Level | Displayed Name | View post | Comment | Like | Receive notification | Create new posts | Edit posts | Delete posts | 
+------ | ------------------- | ------------ | ----------- | ----- | ---------------------- | -------------------- | ------------| -------------
+0       | 會員                    | ✅ | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ 
+1       | 作者                    | ✅ | ✅ | ✅ | ✅ | ✅ | him/herself | him/herself | him/herself |
+8       | 管理員                | ✅ | ✅ | ✅ | ✅ | ✅ | all | all | all
+9       | 站長                    | ✅ | ✅ | ✅ | ✅ | ✅ | all | all | all 
+
+#### Get User's Profile with a Specific Username
+Use the following endpoint to get a user's profile with a specific username.
+```
+/ajax/user.php?username={username}
+```
+The response contains
+- the username(```username```)
+- the displayed name(```name```)
+- user's level number(```level```)
+- displayed name of the user's level number(*note: in unicode*)(```role```)
+- the hash value of the user's email(*for surcurity reason, Cavern API won't provide developers with user's email*)(```hash```)
+- whether the user is muted(```muted```)
+- the number of posts the user created(```posts_count```)
+- whether **you** are in a logged in state(```login```)
+- fetch series(```fetch```)
+
+```json
+{
+    "username":"ExampleUsername",
+    "name":"ExampleName",
+    "level":8,
+    "role":"\u7ba1\u7406\u54e1",
+    "hash":"32c018e02c34cf3fddfbebba6b44c5fc",
+    "muted":false,
+    "posts_count":25,
+    "login":false,
+    "fetch":1570285748411
+}
+```
+
+Again, to see full documentation, please visit our [reference](reference.md)
diff --git a/reference.md b/reference.md
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