WhatsApp is rolling out video calling today to its billion-plus monthly users. That’s basically the entire story — if you’d like to use it, update the app, open a chat, and tap the familiar video camera icon in the top-right corner. The video chat results look like the video chatting you’ve done before on FaceTime, Skype, Facebook Messenger, or Google Duo: two faces, one in a smaller window, with a handful of small features for changing the position of the chat windows or turning the camera around.

That video calls took until November 2016 to arrive on WhatsApp reflects the app’s cautious — some might say glacial — approach to product development. WhatsApp launched in 2009, but group chats didn’t come until two years later, and voice calls didn’t come until four years after that.

But 2016 has been unusually productive for WhatsApp, which Facebook bought in 2014 for $22 billion. This year the company introduced a desktop client, end-to-end encryption, and features for writing and drawing on top of photos. The company also wants to mingle its data with Facebook’s, so as to eventually make money from businesses chatting with you on WhatsApp, but Europe is having none of it.

That it took seven years for WhatsApp to add video calling likely reflects both the expense of doing so and the fact that many of its users around the world don’t have access to the high-bandwidth connections or data plans that would support it. And if version 1.0 looks basic, the company says it will evolve. “We will try to be the best video calling platform out there,” Manpreet Singh, WhatsApp’s lead mobile engineer, told me.

Last month at The Wall Street Journal’s tech conference I asked WhatsApp’s co-founders whether they felt pressure to make an app renowned for its simplicity more complex to allow for the features that make competitors like Snapchat more expressive. CEO Jan Koum told me he’s trying to strike a balance — but that lately the balance has tipped toward adding new avenues for expression. If nothing else, the arrival of video calling shows that those avenues are now under construction.