Instant messaging between desktops and phones hasn’t exactly taken off despite the ubiquity of both. There is Skype. Microsoft has done a good job of making it available everywhere, but most instant messengers are limited to either the PC or mobile phones, and PCs do a surprisingly bad job of supporting SMS texting.

Well, things took a step forward now that WhatsApp, a popular smartphone instant messenger, has finally launched on PC and Mac. The smartphone app, which Facebook bought for an incredible $19 billion last year, has over a billion users worldwide.

Up to now, if you didn’t have it on your smartphone, you had to use the Web site, WhatsApp Web. The desktop app, like the Web site and smartphone app, is designed as “an extension of your phone,” as the company put it, synchronizing your conversations and messages between the two devices.

The desktop app works much like WhatsApp Web. You can send messages, pictures and other attachments, record voice messages, and manage your message history. The experience is largely the same as the smartphone version.

Although the app says it does not support Windows 7, only Windows 8 and 10 along with Mac OS X 10.9, it installed just fine on my Windows 7 machine and started right up without a hitch.

Also, you must be an active WhatsApp smartphone user to run it on your PC. You can’t be a PC-only user. Adding to the strangeness, when you first log in to the app, you’ll need to scan a QR code on your PC screen using the WhatsApp mobile app. Once you do, your PC and phone are in sync.