To access it, users have to go to the website web.whatsapp.com and scan in a QR code from the Whatsapp menu in their phone. This creates a connection between the computer and the phone.
Using Whatsapp on a computer also requires the smartphone being regularly online, since the PC essentially just mirrors what appears on the phone. The service will not work if the phone is inactive.
Nor will it work with iOS devices: The web app will only work with Android, Windows Phone, Blackberry and an old version of Nokia’s S60, because of limitations with the Apple platform. Use of the new service also requires having the most up-to-date version of Whatsapp.
WhatsApp is the world’s most popular instant-message service, with more than 700 million active users.