diff --git a/README.md b/README.md
index 15edce8..a92d79d 100644
--- a/README.md
+++ b/README.md
@@ -8,9 +8,21 @@ The PHP file is used to create the basic setup, the 3 lists, the button and the
 
 Nothing but pure PHP / JS was used in order to use it the easiest way possible, without having to deal with any framework.
 
-###### What's missing ######
+##### What's missing #####
 The XML file is currently filled with false content. The same image and description is used for everything. The XML format is described further.
 
+## How the files work ##
+#### PHP file ####
+Read the XML and return the HTML code of the calculator.
+#### JS file ####
+Everything is in one file so it's easier to implement, however the code inside the file is divided into several parts so it's still easy to read and edit:
+* **Lists related** - Functions related to the "select" lists.
+* **Skills related** - Functions related to anything that touches specific skills (highlight selected skills, display details, ...).
+* **Points related** - Functions related to the points count.
+* **URL/Skills related** - Functions related to the creation of the link, and reading the parameter to display a specific build.
+
+It is also worth mentioning that the **parentNode** / **childNodes** combination has been abused a lot, so changing casually the HTML would most likely break the entire thing.
+
 ## Implement the calculator ##
 It's very easy, all you need to do is include the PHP file, the JS file and the CSS file.
 ```php
@@ -23,4 +35,3 @@ Then you call the **getTree()** method to generate the 3 lists and everything, a
 ```php
 echo $AASkillsCalculator->getTree();
 ```
-After this, you are good to go.