diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..1211bb6
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,4 @@
+language: cpp
+os: linux
+script:
+    - make
\ No newline at end of file
diff --git a/Inventory.cpp b/Inventory.cpp
index 57964b4..828dff6 100644
--- a/Inventory.cpp
+++ b/Inventory.cpp
@@ -4,7 +4,10 @@
 
 using std::string;
 using std::ostream;
+using std::cout;
+using std::endl;
   
+// Inventory class: name of item, price, amount
 Inventory::Inventory(string name, float price, int count)
 {
   m_name = name;
@@ -12,9 +15,21 @@ Inventory::Inventory(string name, float price, int count)
   m_in_stock = count;
 }
 
+// When user chooses to make a sale
 void Inventory::sell()
 {
-  m_in_stock--;
+  // Substract one from invetory after a sale.
+  if(m_in_stock > 0)
+  {
+    m_in_stock--;
+  }
+
+  // When no inventory is left to sell, send error.
+  else
+  {
+    cout<<"Sorry, that item is out of stock\n"<<endl;
+  }
+  
 }
 
 ostream& operator<<(ostream& stream, const Inventory& item)
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..70fa46b
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+Travis CI Badge:
+
+[![Build Status](https://travis-ci.com/asheelamagwili/Inventory.svg?branch=master)](https://travis-ci.com/asheelamagwili/Inventory)
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
index 236d4ec..a6e03aa 100644
--- a/main.cpp
+++ b/main.cpp
@@ -8,12 +8,14 @@ using std::string;
 int main()
 {
   char choice = 'q';
+  // Initial amount of the stock: Name of stock, price, amount
   Inventory stock("Cupcake",2.99,100);
 
   do
   {
     cout<<"\nMENU\n====\n(S)ell item\n(Q)uit\n>";
     cin>>choice;
+    // Take user input for Sell until user chooses to Quit
     if( choice == 'S' || choice == 's' )
     {
       stock.sell();