Digital Plastic Surgery
People want to look good in photographs, and photographers have a lot of tools at their disposal to help them. Make-up and lighting can improve a person's appearance as the shot is being taken, but after the picture has been captured, image manipulation software (most famously Adobe's Photoshop program) can work even more wonders.
Wrinkles can be erased, blemishes removed, skin tone evened out, fat rolls melted away, breasts enlarged, and tummies shrunk, all with the click of a mouse. This is known as 'Digital Plastic Surgery,' and it's become such a common practice that it's rare to find a photo in a fashion or entertainment magazine that hasn't been touched up in some way.
Few people have a problem when photo editors remove a few pimples or stray hairs from a celebrity's face. But when photos are changed so much that the end result looks significantly different than the real-life person, that does still raise eyebrows (figuratively speaking).
In extreme cases, a photo editor might even opt for 'total body replacement,' which involves digitally transplanting a person's head onto someone else's body.
Of course, Digital Plastic Surgery dates back long before the arrival of image manipulation software. The practice is almost as old as photography itself. In the pre-Photoshop era, it was simply Darkroom Plastic Surgery.