You can access WhatsApp on both your phone and your computer. You can use WhatsApp on your computer in two ways:
WhatsApp Web and WhatsApp Desktop are computer based extensions of the WhatsApp account on your phone. The messages you send and receive are fully synced between your phone and your computer, and you can see all messages on both devices. Any action you take on the phone will apply to WhatsApp on your computer and vice versa.
Go to https://www.whatsapp.com/download from your computer's browser or download it from Apple App Store. WhatsApp can only be installed on your computer if your operating system is Windows 8 (or newer) or Mac OSX 10.9 (or newer). Since WhatsApp Desktop runs natively on your desktop, you'll have support for native desktop notifications, better keyboard shortcuts and more. If your operating system isn't supported, you may use WhatsApp on your browser instead.
For more information regarding installing WhatsApp on your computer, please read this article.
Open https://web.whatsapp.com in your Chrome, Firefox, Opera, Safari or Edge browser and scan the QR code by using the WhatsApp app on your phone. Due to browser limitations, some features may be missing on WhatsApp Web.
For more information regarding using WhatsApp Web, please read this article.