diff --git a/docs/threat_model/index.rst b/docs/threat_model/index.rst
index e8f09b9..b5ede69 100644
--- a/docs/threat_model/index.rst
+++ b/docs/threat_model/index.rst
@@ -1,5 +1,12 @@
 Threat Model
-=============
+============
+
+Threat modeling is an important part of Secure Development Lifecycle (SDL)
+that helps us identify potential threats and mitigations affecting a system.
+
+In the next sections, we first give a description of the target of evaluation
+using a data flow diagram. Then we provide a list of threats we have identified
+based on the data flow diagram and potential threat mitigations.
 
 .. toctree::
    :maxdepth: 1
@@ -7,6 +14,7 @@
    :numbered:
 
    threat_model
+   threat_model_spm
 
 --------------