WhatsApp now has over a billion users worldwide, and today, it's upgrading its user experience for them by extending support for messaging to PCs. It has announced the launch of its desktop app, which it says will allow users to "stay in touch anytime and anywhere - whether on your phone or computer at home or work."
Much like WhatsApp Web, the desktop app is designed as "an extension of your phone", synchronizing your conversations and messages between the two devices.
The app is available now for Mac devices running OS X 10.9, and for Windows PCs too. However, WhatsApp hasn't launched a new app for Windows 10, built on Microsoft's Universal Windows Platform; instead, it's a classic 'desktop app', which it says is supported on versions back to Windows 8.
To download the app, visit this site on your desktop browser; then start it up, and scan the QR code using WhatsApp on your phone ("look for WhatsApp Web menu under Settings").