'Film grain looks better' is a statement that carries more than nostalgia. It is usually said by people who grew up with grain and are responding to a texture that carries emotional associations. That's real and worth acknowledging.
It is also an incomplete account of why grain produces the specific response it does - and the complete account is more interesting.
WHAT FILM GRAIN PHYSICALLY IS
Film grain is the visible texture of the silver halide crystals in photographic film stock. When light hits the film, these crystals are activated randomly - not uniformly - which means that the same image captured on two different frames of the same film stock will have the grain pattern in slightly different positions. The grain is organic, random, slightly different in every frame.
This means that even a static image on film is not technically static. The grain shifts subtly between frames, creating a micro-movement in the image that digital photography, which captures the same information identically in each frame, does not produce. The eye processes this micro-movement as presence - as the sign that the image was physically in contact with light, that the light came from somewhere real.
THE ORGANIC RANDOMNESS ARGUMENT
The argument for grain's aesthetic superiority to clean digital imagery is essentially an argument about organic randomness. Digital imagery is technically perfect in the way that a synthesised instrument is technically perfect - every note is exactly the right frequency, every pixel is exactly the right colour. The perfection is also an absence: the absence of the physical imperfection that tells you the sound came from a vibrating string, or the image came from light reflected off an actual surface.
Grain is the evidence of the photographic process - the visible record of the light's contact with the film. When that evidence is present, the image carries an indexical quality: it is pointing back at something that was physically there when the photograph was taken. This is what Roland Barthes called the punctum of photography - the detail that arrests the eye and produces the sense that this image was of something real.
WHAT DIGITAL NOISE IS AND ISN'T
Digital cameras produce their own version of grain - digital noise, which is the electronic artifact of shooting in low light. Digital noise looks similar to film grain to the casual eye but is technically different: it is distributed differently across the colour channels, it is less organic in its pattern, and it has a different relationship to the image's tonal range. Film grain is part of the image. Digital noise is interference with the image.
The contemporary practice of adding digital grain to footage shot on digital cameras - done in the colour grade to replicate the film grain aesthetic - is adding the appearance of indexicality without the substance. It makes the image look like it was in contact with something real. It wasn't. The viewer's perception may not distinguish; the ontological situation is different.
MUBI AND THE PRESERVATION QUESTION
The streaming platform that takes this most seriously is MUBI, which specifically presents film in its intended visual quality - grain intact rather than digitally smoothed away in the transfer process. The smoothing of grain in streaming transfers is a quality decision that prioritises apparent sharpness over archival accuracy. MUBI's decision to preserve grain is the archival decision, the decision to show the film as it was photographed rather than as post-production processing has made it look. The difference is audible to anyone who has seen the same classic film in a good 35mm print and a smoothed streaming transfer.
Grain is the evidence of the photographic process - the visible record of the light's contact with the film.