Whatsapp introduced its Web Service last day. Right now anyone who using the Whatsapp can access it through desktop or via tablet.
How to launch Whatsapp on Web:
1) Go to your Play Store/Window/IOS, update your current Whatsapp Version.
2) Then open your updated Whatsapp
3) Click Menu
4) Click “Whatsapp Web”
5) Then go to https://web.whatsapp.com on your computer
6) By using the QR scanner scan the QR Code in the web.
7) Then it will automatically login your whatsapp on web.
8) Activate Desktop Alerts ticked to get the message notification on Desktop.
Note : The main problem is that, you have to keep your mobile Whatsapp online to get access on the web. Now its only available on Google Chrome.