diff --git a/book/chapter-06-gbapp-reference.md b/book/chapter-06-gbapp-reference.md
index 3dc6de36..d67f254c 100644
--- a/book/chapter-06-gbapp-reference.md
+++ b/book/chapter-06-gbapp-reference.md
@@ -133,6 +133,13 @@ static getDialogs(bot: BotAdapter, min: GBMinInstance) {
 
 1. Visit https://<SITENAME>.scm.azurewebsites.net/api/vfs/LogFiles/Application/index.html
 
+### Fork concept
+##fork concept
+
+A fork or branch it happens when a developer (or a group of developers) starts an independent project based on the code of an existing project, that is, when a software is developed based on another, already existing, without the discontinuity of the latter.
+
+The term is particularly used in free or open source software, when a division occurs because of different goals or personality fights. Some see bifurcations as a weakness in free software, but others believe that they demonstrate the adaptability of the model.
+
 ## Tooling
 
 ### JavaScript