A JPEG is a way of storing images on a digital device such as IP CCTV cameras, digital cameras and mobile phones. JPEG is a compressed image format which uses a fractal-based algorithm to compress data, giving a greatly reduced file size compared to image dimensions. The compression is adjustable but greater compression ratios will result in loss of data and as such grainier pictures.
The JPEG format is most suited to busy images with lots of colour and in IP cameras is typically used for snapshots from the video stream.
JPEG stands for Joint Photographic Experts Group, who created the format when trying to produce a smaller file size for transmitting images across the internet. Most IP CCTV cameras support this format due to the reduced file size which helps to reduce bandwidth and hardware usage.