diff --git a/README.md b/README.md
index 522a60f..7195e3a 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,16 @@ Actions for the gCubeActions Pipeline
 
 Container for Actions executed with the gCubeActionExecutor pipeline.
 
+## Action
+An Action is a script that is executed on a selected git repository.
+Every command in the Action must be written considering the root folder of the repository as working folder.
+
+### Exit Code
+An Action is successful if it returns 0 as exit code. Any code different from 0 makes the Action fails and halts the execution
+of the pipeline process.
+An exit code can be returned in any point of the Action by invoking the <code>exit code</code> command.
+Unless exit is used, the exit code of the Action is the one returned by the last command of the Action.
+
 ## List of Repositories
 
 Each action is executed on a list of repositories. The expected format of the file with the list on repo name per file.