To log in to WhatsApp on WhatsApp Web, WhatsApp Desktop, or Portal, you need to use your phone to scan the QR code.

1. Open WhatsApp on your phone.
   • Android: On Home screen on top left tap More options.
   • iPhone: Go to WhatsApp Settings.
2. Tap WhatsApp Web or WhatsApp Web/Desktop.
   • Android: Tap LINK A DEVICE. Follow the on-screen instructions if your device has biometric authentication.
   • iPhone: Tap Link a Device > OK. On iOS 14 and above, use Touch ID or Face ID to unlock.
3. Go to the website https://web.whatsapp.com
4. Select the checkbox next to Keep me signed in on the QR screen on your computer or Portal to stay logged in on this device.

Whatsapp Web - is it safe? I mean my mobile is always with me, but chances are my PC could be accessed by colleagues (which does not happen mostly, but just in case ) when I am away.

Whatsapp Web can only be activated with the help of your own device where you are using Whatsapp. As a precaution, it is not recommended to use Whatsapp Web on any public computer. In case you have to use it, always logout after usage.

If you are doubtful, open will have to open WhatsApp on your device (mobile in this case) and just tap on the three dots at the top right corner. Then tap on "WhatsApp Web".
If you have not logged out of your account, you will see an option as below. Just tap on the device from which you want to logout.

I am sure lots of people dont know and hence allow their WhatsApp getting hacked. Thanks PRE for updating this info to the users.