diff --git a/book/chapter-06-gbapp-reference.md b/book/chapter-06-gbapp-reference.md
index 6a7c1c75..1f0c40d2 100644
--- a/book/chapter-06-gbapp-reference.md
+++ b/book/chapter-06-gbapp-reference.md
@@ -128,6 +128,9 @@ static getDialogs(bot: BotAdapter, min: GBMinInstance) {
     *Figure 1 - How to build dialogs in General Bots using TypeScript*
 
 
+## Fork concept
+
+is the implementation of new software based on existing software. The branch takes advantage of the data already used in other software to generate a new one.
 
 ## How To...