Apple is taking a significant step towards making iPhone a(n even more) serious camera for professionals in iOS 10 by adding support for RAW photo files. The information was included in a slide during Monday's World Wide Developer Conference keynote, and TechCrunch reported details from a WWDC session confirming RAW support in iOS 10.
RAW is a file format that stores photograph information without compressing or otherwise altering it. Outside of photography professionals and enthusiasts, you may have seen some of the many updates Apple issues that add RAW support for specific DSLR models every few months.
RAW is important to professionals because it gives them them the most information to work with when processing their images. Every pixel is there and none of them have been done away with to make the file smaller, which is what JPEG does—it intelligently throws away "unneeded" pixels that the human eye isn't likely to miss, making files significantly smaller.
Apple's iPhone is already one of the world's most popular cameras, and the device is increasingly used in professional settings. But supporting RAW will eliminate a significant barrier to some high-end applications. I'm not saying that DLSRs with big lenses are going to be put out to pasture, but RAW support in iPhone will mean the device creeps into more and more professional settings.
TechCrunch noted some other details, starting with the fact that developers will still have to add RAW support to their camera applications—and Apple hasn't specified whether or not the built-in app will support it (I'd be shocked if it didn't). It will work only with the rear camera, store those RAW images using Adobe's Digital Negative files (DNG), and work only iPhone 6/6s, iPhone 6/6s Plus, iPhone SE, and iPad Pro (9.7-inch). It will also be able to shoot RAW and JPEG files simultaneously like most DLSRs.