The HEIC format was developed by the Moving Pictures Expert Group (MPEG) in the middle of 2015. One reason Apple made HEIC the default format on all iPhones is because it requires around half the storage of a JPG file of comparable quality. A HEIC file also contains an alpha channel for transparent images, a depth map for LiDAR scans, depth estimates, and more. It provides more versatility overall than a JPG file.
For example, a JPEG file needs 10MB of space to have the same visual quality as a 5MB HEIC file. Even though 5MB on today's smartphones doesn't sound like much, when you consider thousands of images, the overall space-saving can reach gigabyte levels. Additionally, it causes speedier upload and file transfer rates on the internet. The HEIC file format is supported by Adobe Photoshop and Lightroom, two standard editing programs used by photographers.
Although HEIC format capture is enabled by default on iPhones and iPads, you can disable it. To turn on or off the HEIC format on your iOS device, Open Settings/Camera/Formats/Most Compatible.