With each new iPhone, Apple introduces a new camera feature. This year's feature is what the company calls Live Photos. A live photo consists of 1.5 seconds of video, the photo, then an additional 1.5-seconds of video.
The end result is a standard photo a first glance, but when touched, the photo comes to life showing the entire 3-second clip.
The Live Photos feature is enabled by default, but luckily it's easy to turn off.

When you launch the camera app, you'll see a new icon, made up of three concentric circles at the top of your screen. If the icon is yellow (or gold), Live Photos is currently turned on. To turn it off, simply tap on the icon. You can always turn it back on by following the same steps. It's one feature that's easy to quickly turn on or off.

What if you took a photo and forgot to turn off Live Photos? You can remove the video portion by editing the photo on your iOS device. When viewing a Live Photo, tap on Edit, and then make an adjustment. I've found any changes made using the tools will prompt an alert, letting you know any changes made will remove the video portion. On the other hand, using the "magic wand" to automatically optimize the photo will not remove the video.