diff --git a/background.js b/background.js
index 924b2d31..21199ed1 100644
--- a/background.js
+++ b/background.js
@@ -1,6 +1,6 @@
-chrome.tabs.onUpdated.addListener(
+chrome.tabs.onUpdated.addListener( // On tab update
   function(tabId, changeInfo, tab) {
-    if (changeInfo.url && id = youtube_parser(changeInfo.url)) {
+    if (changeInfo.url && id = youtube_parser(changeInfo.url)) { // If URL changed and is youtube video message ContentScript the video id
       chrome.tabs.sendMessage( tabId, {
         message: 'ytvideoid',
         id: id
@@ -8,7 +8,7 @@ chrome.tabs.onUpdated.addListener(
     }
   }
 );
-function youtube_parser(url) {
+function youtube_parser(url) { // Return video id or false
     var regExp = /^.*((youtu.be\/)|(v\/)|(\/u\/\w\/)|(embed\/)|(watch\?))\??v?=?([^#\&\?]*).*/;
     var match = url.match(regExp);
     return (match && match[7].length == 11) ? match[7] : false;