Starting with iOS 11, iPhones save images in HEIC file type by standard. HEIC — Apple's HEIC format — is highly efficient: it creates images with approximately half the storage of similar JPEGs while maintaining great image quality. However there is a significant catch. HEIC is an Apple-centric file type not broadly compatible beyond the App

Many users have saved an photo from the web and discovered it saved with a .jfif file extension rather than the usual .jpg, this is common. JFIF — short for JPEG File Interchange Format — is a specification defining how JPEG image data is stored. In practical terms, a JFIF photo is a JPEG photo. The .jfif suffix shows up primarily when savin