This means that every time when you visit the website, your WhatsApp chats will open. Once you're connected on WhatsApp Web, it won't logout even after you've closed the browser or even if you have turned off your system. For WhatsApp Web to work, your phone on which your WhatsApp account is active needs to be turned on along with having an active internet connection.

WhatsApp Web won't work on your computers and tablets if the mobile number with which it is synced is turned off. You now have WhatsApp running as an app on your computer. This is to be done so that you don't have to scan the code each and every time you open the app. Before scanning the code, make sure you check the Keep me signed in option right below the QR code.Similarly, if you have an iPhone, open WhatsApp > tap Settings > followed by tapping WhatsApp Web. If you have an Android smartphone, open WhatsApp > tap the vertical three-dots icon and select WhatsApp Web. Scan the QR code from your phone by opening WhatsApp.You'll now see the familiar QR code, just like the one you see when you open WhatsApp Web on a browser.Once your file is downloaded, install it on your system and open it.

Note, that the website automatically detects whether you're using a Mac or a Windows PC, so you don't really have to look for a particular version for your system.

Under Download WhatsApp for Mac or Windows PC, click the green Download button.

If you prefer having WhatsApp as an app for your desktop, rather than going to your web browser and loading WhatsApp Web each time you have closed the browser, follow these steps: WhatsApp Web app: How to download and use with QR code

How does whatsapp web app work