diff --git a/src/app/factory.cpp b/src/app/factory.cpp
index 2efed51..aa4caa4 100644
--- a/src/app/factory.cpp
+++ b/src/app/factory.cpp
@@ -15,7 +15,6 @@ Factory::Factory() {
 void Factory::initialize() {
     Trace::initialize();
 
-    // TODO: Initialize factory attributes here
 
 
 #if defined(TOUCHGFX_ENABLED) && (TOUCHGFX_ENABLED != 0)
@@ -27,24 +26,21 @@ void Factory::initialize() {
 void Factory::build() {
     Trace::out("Factory: Creating app components...");
 
-    // Start state machine(s)
-
+    // Start SM of ButtonEventLogger & ButtonsController
     buttonEventLogger_.startBehavior();
     ButtonsController::getInstance()->startBehavior();
 
+    // Register CallBack of ButtonController with himself for the provider and onButtonChangeState for the CallBack Method
     ButtonsController::getInstance()->registerCallback (
     		ButtonEventsHandler::getInstance(),
 			(interface::ButtonsControllerCallbackProvider::CallbackMethod) &ButtonEventsHandler::onButtonChangeState
 			);
 
-    buttonEventLogger_.startBehavior();
+    // Subscribe ButtonEventLogger to ButtonEventsHandler & start SM of ButtonEventsHandler
     ButtonEventsHandler::getInstance()->subscribe(&buttonEventLogger_);
     ButtonEventsHandler::getInstance()->startBehavior();
 
 
-	
-    // TODO: Start state-machines here
-
 #if defined(TOUCHGFX_ENABLED) && (TOUCHGFX_ENABLED != 0)
     getTouchGfxTask().start();
 #endif
diff --git a/src/app/factory.h b/src/app/factory.h
index 1871ebc..1043d8d 100644
--- a/src/app/factory.h
+++ b/src/app/factory.h
@@ -11,8 +11,6 @@
 #include "platform/f7-disco-gcc/board/ButtonsController.h"
 #include "mdw/button/ButtonEventsHandler.h"
 
-// TODO: Add C++ specific includes here
-
 namespace app {
 
 /**
@@ -30,7 +28,6 @@ public:
 #endif
 
 protected:
-    // TODO: Add static attributes here
     static ButtonEventsLogger buttonEventLogger_;
 };
 
diff --git a/src/xf/core/XFState.cpp b/src/xf/core/XFState.cpp
index ca3aab3..deafda9 100644
--- a/src/xf/core/XFState.cpp
+++ b/src/xf/core/XFState.cpp
@@ -13,40 +13,52 @@
 
 XFState::XFState(XFBehavior* behavior)
 	: pBehavior(behavior) {
+	/*
+	 * Initialise behavior of this state on the constructor.
+	 * Can't be null !
+	 */
 	assert(behavior != nullptr);
-	cbState_ = nullptr;
-	cbEntry_ = nullptr;
-	cbExit_ = nullptr;
-	cbEvState_ = nullptr;
-	cbEvEntry_ = nullptr;
-	cbEvExit_ = nullptr;
 }
 
 void XFState::addTransition(XFEvent::XFEventType type, const int evid, const int time, XFState* state) {
 	assert(state != nullptr);
+	/*
+	 * Create a transition with his Type, ID, time if Timeout and the state to be set when this transition happen
+	 * Push the transition on the list of transition of the event
+	 * Pointer State can't be null
+	 */
 	transition t;
+	t.evType = type;
 	t.evid = evid;
 	t.time = time;
-	t.evType = type;
 	t.nextState = state;
 	transitions_.push_back(t);
 }
 
 XFEventStatus XFState::changeState(XFState* state) {
-	pBehavior->curentXFState_ = state;
+	// Change current state of the behavior
+	pBehavior->currentXFState_ = state;
+
+	// Set state is changed
 	pBehavior->changeXFState = true;
+
+	// Return the event status as consumed
 	return XFEventStatus::Consumed;
 }
 
 XFEventStatus XFState::onState(const XFEvent* ev) {
 
+	// Execute onState callBack without parameter if it's defined
 	if(cbState_ != nullptr) {
 		(pBehavior->*cbState_)();
 	}
+
+	// Execute onState callBack with event as parameter if it's defined
 	if(cbEvState_ != nullptr) {
 		(pBehavior->*cbEvState_)(ev);
 	}
 
+	// Test each transition and change state if one is actual transition
 	for(transition t : transitions_) {
 
 		switch(ev->getEventType()) {
@@ -71,21 +83,25 @@ XFEventStatus XFState::onState(const XFEvent* ev) {
 
 		}
 
-
 	}
 
+	// Return event status as notConsumed if actual event isn't on the list of transitions
 	return XFEventStatus::NotConsumed;
 }
 
 void XFState::onEntry(const XFEvent* ev) {
+
+	// Execute onEntry callBack without parameter if it's defined
 	if(cbEntry_ != nullptr) {
 		(pBehavior->*cbEntry_)();
 	}
 
+	// Execute onExit callBack with event as parameter if it's defined
 	if(cbEvEntry_ != nullptr) {
 		(pBehavior->*cbEvEntry_)(ev);
 	}
 
+	// If a timeout is on the list of transition start it with is own delay
 	for(transition t : transitions_) {
 
 		if(t.evType == XFEvent::XFEventType::Timeout) {
@@ -95,14 +111,18 @@ void XFState::onEntry(const XFEvent* ev) {
 	}
 }
 void XFState::onExit(const XFEvent* ev) {
+
+	// Execute onExit callBack without parameter if it's defined
 	if(cbExit_ != nullptr) {
 		(pBehavior->*cbExit_)();
 	}
 
+	// Execute onExit callBack with event as parameter if it's defined
 	if(cbEvExit_ != nullptr) {
 		(pBehavior->*cbEvExit_)(ev);
 	}
 
+	// If a timeout is on the list of transition and isn't the actual event, stop it
 	for(transition t: transitions_) {
 
 		if(t.evType == XFEvent::XFEventType::Timeout) {
diff --git a/src/xf/core/behavior.cpp b/src/xf/core/behavior.cpp
index 219702e..6d94267 100644
--- a/src/xf/core/behavior.cpp
+++ b/src/xf/core/behavior.cpp
@@ -84,16 +84,21 @@ XFBehavior::TerminateBehavior XFBehavior::process(const XFEvent * pEvent)
 }
 
 XFEventStatus XFBehavior::processEvent(){
+
+	/*
+	 * Basic double switch pattern but not switch on an enum but on Object XFState
+	 */
+
 	XFEventStatus eventStatus = XFEventStatus::Unknown;
 	const XFEvent * ev = getCurrentEvent();
 
-	oldXFState_ = curentXFState_;
+	oldXFState_ = currentXFState_;
 
-	eventStatus =  curentXFState_->onState(ev);
+	eventStatus =  currentXFState_->onState(ev);
 
 	if(changeXFState){
 		oldXFState_->onExit(ev);
-		curentXFState_->onEntry(ev);
+		currentXFState_->onEntry(ev);
 	}
 
 	return eventStatus;
diff --git a/src/xf/include/xf/XFState.h b/src/xf/include/xf/XFState.h
index e27844e..2d6f134 100644
--- a/src/xf/include/xf/XFState.h
+++ b/src/xf/include/xf/XFState.h
@@ -97,12 +97,12 @@ protected:
 	} transition;
 	std::list<transition> transitions_;
 
-	callback cbState_;
-	callback cbEntry_;
-	callback cbExit_;
-	callbackEv cbEvState_;
-	callbackEv cbEvEntry_;
-	callbackEv cbEvExit_;
+	callback cbState_ = nullptr;
+	callback cbEntry_ = nullptr;
+	callback cbExit_ = nullptr;
+	callbackEv cbEvState_ = nullptr;
+	callbackEv cbEvEntry_ = nullptr;
+	callbackEv cbEvExit_ = nullptr;
 
 };
 
diff --git a/src/xf/include/xf/behavior.h b/src/xf/include/xf/behavior.h
index 1ff1826..598a1db 100644
--- a/src/xf/include/xf/behavior.h
+++ b/src/xf/include/xf/behavior.h
@@ -55,7 +55,7 @@ public:
 protected:
     /**
      * Executes the current event in its implemented behavior.
-     * This method needs to be overridden to implement the
+     * This method can be overridden to implement the
      * behavior (i.e. state machine) needed.
      */
     virtual XFEventStatus processEvent();
@@ -100,9 +100,20 @@ protected:
     const XFEvent * pCurrentEvent_;					///< Reference to actually processed event.
 
 protected:
+    /**
+     * Behavior have at least an Initial State.
+     */
     XFInitialState stInitial;
-	XFState* curentXFState_ = &stInitial;
+
+    /**
+     * Pointer for the curent and old state of this behavior
+     */
+	XFState* currentXFState_ = &stInitial;
 	XFState* oldXFState_ = &stInitial;
+
+	/**
+	 * Keep in trace when state is changed (have to be set to true in every processEvent
+	 */
 	bool changeXFState = false;
 
 };