diff --git a/01_Day_Introduction/01_day_starter/datatypes.js b/01_Day_Introduction/01_day_starter/datatypes.js
new file mode 100644
index 0000000..1572678
--- /dev/null
+++ b/01_Day_Introduction/01_day_starter/datatypes.js
@@ -0,0 +1,16 @@
+let firstName = 'Matthew'
+let yourName = "ODB"
+let yourAge = 100
+let myAge = 21
+const PI = 3.14
+let isMarried = true
+let nullValue = null
+let notDefined
+let anotherOne
+let andAnotherOne
+let undefinedVarFour
+array = [firstName, myAge, PI, isMarried, nullValue, notDefined]
+array.forEach(logType)
+function logType(variable){console.log(typeof variable)}
+console.log(`${firstName} is ${myAge} years old`)
+console.log(`${yourName} is ${yourAge} years old, what an oldie!`)
diff --git a/01_Day_Introduction/01_day_starter/index.html b/01_Day_Introduction/01_day_starter/index.html
index 43831f6..31f817b 100644
--- a/01_Day_Introduction/01_day_starter/index.html
+++ b/01_Day_Introduction/01_day_starter/index.html
@@ -11,9 +11,10 @@
         <button onclick="alert('Welcome to 30DaysOfJavaScript!');">Click Me</button>
         <script src="./helloworld.js"></script>
         <script src="./introduction.js"></script>
-        <script src="./varaible.js"></script>
+        <script type="module" src="./varaible.js"></script>
         <script src="./main.js"></script>
+        <script type="module" src="./datatypes.js"></script>
 
 </body>
 
-</html>
\ No newline at end of file
+</html>
diff --git a/01_Day_Introduction/01_day_starter/introduction.js b/01_Day_Introduction/01_day_starter/introduction.js
index 316199c..77d136e 100644
--- a/01_Day_Introduction/01_day_starter/introduction.js
+++ b/01_Day_Introduction/01_day_starter/introduction.js
@@ -1 +1,8 @@
-console.log('Welcome to 30DaysOfJavaScript')
\ No newline at end of file
+// comments can make code readable
+console.log('Welcome to 30DaysOfJavaScript')
+// display Welcome to 30DaysOfJavaScript
+/* comments can make code readable
+  easy to reuse
+  and informative
+  this is a multiline comment
+*/
diff --git a/01_Day_Introduction/01_day_starter/varaible.js b/01_Day_Introduction/01_day_starter/varaible.js
index 62558cb..bc6a257 100644
--- a/01_Day_Introduction/01_day_starter/varaible.js
+++ b/01_Day_Introduction/01_day_starter/varaible.js
@@ -1,11 +1,13 @@
 // Declaring different variables of different data types
-
-let firstName = 'Asabeneh'    // first name of a person
-let lastName = 'Yetayeh'      // last name of a person
-let country = 'Finland'       // country
-let city = 'Helsinki'         // capital city
-let age = 100                 // age in years
-let isMarried = true
+const variablesList = () => {
+let firstName = 'Asabeneh'    // first name of a person string
+let lastName = 'Yetayeh'      // last name of a person string
+let country = 'Finland'       // country string
+let city = 'Helsinki'         // capital city string
+let age = 100                 // age in years number
+let isMarried = true          // boolean value
+let nullValue = null          // null value
+let notDefined                // returns not defined
 
 // Declaring variables with number values
 
@@ -18,3 +20,5 @@ const PI = 3.14              // geometrical constant
 let name = 'Asabeneh',     //name of a person
   job = 'teacher',
   live = 'Finland'
+}
+export { variablesList };