JPG or JPEG is acronym for Joint Photographic Experts Group, a committee which created the standard. JPEG is a commonly used method of lossy compression for digital images. The JPEG standard specifies how an image is compressed into a stream of bytes and decompressed back into an image.
Exchangeable Image file Format (Exif) used by digital cameras and other image capture devices and JPEG File Interchange Format (JFIF) used for transmitting image on world wide, web standards define the most used file formats for interchange of images which are compressed using JPEG standards.
JPEG standard was initially released on 18th September 1992. Original documentation of JFIF states:
"JPEG File Interchange Format is a minimal file format which enables JPEG bitstreams to be exchanged between a wide variety of platforms and applications. This minimal format does not include any of the advanced features found in the TIFF JPEG specification or any application specific file format. Nor should it, for the only purpose of this simplified format is to allow the exchange of JPEG compressed images".
JPEG files have extension of .jpg or .jpeg. The JPEG compression method is generally lossy, which means that some information is lost and can't be restored. These images are not suitable for multiple edits as after each edit some quality or details are lost.
JPEG achieves a compression ratio of 10:1 without losing significant details. This results in smaller file size which allows for easier sharing and storing. The degree to which JPEG file can be compressed is adjustable, this implies that user can choose image quality by choosing compression rate. JPEG files are generally used for photographs and realistic sceneries or paintings.
JPEG files embed ICC color profiles. Most commonly used color profiles are Adobe RGB or SRGB
JPEG image contains sequence of segments each starting with a marker which begins with 0xFF byte, followed by a byte indicating what kind of marker it is.