iPhones can save photos in HEIC or JPG. Apple calls these settings High Efficiency and Most Compatible. High Efficiency uses HEIC to save storage space. Most Compatible uses JPG to reduce problems when sending files to older apps, websites or Windows PCs.
Neither choice is universally correct. HEIC is more efficient. JPG is more widely accepted. The best setting depends on whether you mostly keep photos in Apple Photos or regularly move them into forms, email, Windows folders, CMS uploads and client workflows.
Use HEIC when storage matters
HEIC usually stores similar visual quality in a smaller file than JPG. If you take many photos and mostly view them on Apple devices, HEIC is a good default. It keeps your camera roll smaller and works smoothly inside iCloud and modern Apple apps.
The pain starts when another system rejects HEIC. Some upload forms, older editors and Windows setups still do not open it cleanly. That is when conversion becomes part of the workflow.
Use JPG when compatibility matters
JPG is the safer setting if your photos regularly go to clients, schools, government portals, marketplaces or coworkers on Windows. The files may be larger, but fewer people will ask how to open them.
You can keep HEIC enabled and convert only when needed. That gives you storage savings most of the time and compatibility on demand. The key is using a converter that runs locally if the photos are private.