JPEG file may contain EXIF, IPTC, XMP and other types of metadata. For example these metadata may be important for a photographer who wishes the information about the author won’t be lost during rotating an image.
Some metadata fields should be updated when the image is rotated. Mostly that are dimension, resolution and orientation tags.
CelesteCS Image Lossless Rotator plugin reads original EXIF, IPTC and XMP metadata from JPEG files, updates appropriate tags and writes it to the rotated image file.
Note: even though PNG format supposes using of XMP metadata, copying it for PNG files is not supported.