A raw file records what the sensor captured before the camera applies white balance, contrast, sharpening, noise reduction and compression. It keeps more range at both ends, so the texture in a white shirt that a JPEG would show as plain white, or the folds in black wool that a JPEG would bury in shadow, can still be brought back in editing. Each camera maker has its own raw format; many phones save the open DNG format.
A raw file is not an upload format. Browsers cannot display it, and the few channels that take one convert it with their own default settings, so the look is no longer in the seller's hands. Phones surprise people here: a raw photo skips the phone's usual processing and looks flatter and noisier than the normal photo until it is edited, which is expected and not a fault.
Raw pays off for products that are hard to expose or colour: white and black goods, gloss, metal, and fabrics whose exact shade matters. For everyday listing photos taken in good light, a well-exposed JPEG is usually enough. Where raw is used, the raw file stays as the archive, so that a later export in another size or colour space starts from the full data and not from a compressed copy.