This is a standardised, universal file format for digital photos that can be displayed by practically any device without any kind of conversion. It uses powerful compression to reduce the file size of digital photos so that you can get more on to a memory card or a hard disk, and they’re quicker to transfer. There can be some loss of quality (often invisible to the naked eye), so for ultimate quality many photographers shoot photos in their camera’s RAW format instead. It’s only more advanced cameras that offer this RAW option, and it produces much larger files which you will need to process yourself later on.