WhatsApp Web allows you to access the same account from both mobile and computer devices which are fully synced and accessible from both the devices.
WhatsApp Web is a computer based extension of the WhatsApp account on your phone. It is not another WhatsApp account but simply the same account you are accessing from both the devices. The messages you send and receive are fully synced between your phone and computer and you can see all messages on both devices.
Any action on the phone will apply to WhatsApp Web and vice versa. It is available for Android, iPhone 8.1+, Windows Phone 8.0 and 8.1, Nokia S60, Nokia S40 EVO, BlackBerry and BlackBerry 10 smartphones.
WhatsApp Web allows you to turn on desktop notifications on the browser and get alerts for new messages even when the browser is minimised. It also offers a ‘Log Out’ feature to the users. However, only one web session is allowed at a time; meaning once logged out, you will have to follow all the above steps to log in again.