... or "developing", in the older days!
Here 2 examples, an un-edited photo in the past and an un-edited photo in our digital age (yeah, that's right, the second "image" is part of the program text interpretation of a digital raw photo, only one of several hundred pages per photo, btw... that's how a digital image really looks like):
This is a subject regularly popping up on my Facebook pages. People commenting like "ah that's a filter" etc.
No, it's not, and I'm trying to explain this a bit in this article.
First, a fact that most people are not aware of. Every photograph ever taken has been "edited" (=developed). In older days, a camera exposed a glass or tin sheet covered in light sensitive chemicals to light through a lens. Later to a piece of film, and nowadays it exposes an electronic sensor.
In ALL cases, you get a photo-negative, though in our days it's a so called "raw image". Any such negative has to be transferred to another medium (usually paper) and during this process those images have been fine-tuned to correct contrast, exposure and other properties. All pre-digital photographs you might have seen in old magazines, were subjected to this process.
A similar process happens in your phone or point-and-shoot-camera. The sensor gets light signals and translates those into computer readable language. In those "lesser" cameras, this "raw image" will be "adjusted" to the settings you chose on the camera during the shooting (most people use the "auto mode" for this). The "raw image data" is discarded when the automatic editing process saves the final image. Yes, this is already an actual editing process, even though nobody notices it. The "auto mode" is just a general set of settings (and adjustments), implemented by the programmer who wrote the operating system for your camera or phone - and any digital camera or phone runs on an operating system.
Essentially it's pretty close to a Polaroid image, sometimes good, sometimes bad, but ALWAYS an (automated) edit, regardless if you hit any additional button or not!
More sophisticated cameras can shoot and save in raw mode, which produces an image similar to the old negatives, though it doesn't inverse the colors. It contains all possible image information, regardless which preset (auto mode, manual mode, white balance, ISO, contrast data, etc.) you selected beforehand. Hence those raw images can easily exceed 20, 30, 50 megabytes or even more, compared to a final jpeg image of 5-10 megabyte - I never shoot auto mode, only manual mode, to have full control of the actual shot.
Those raw images, due to the mentioned properties and presets, can look dull, too bright, too dark, etc. and need to be processed (=edited=developed) like a negative in the old days.
A so called (modern day) filter is nothing more than a program preset applied to the whole image. On your phone, such a filter usually dramatically reduces the over all quality of the image. This goes unnoticed, mostly, as those images are usually viewed only on your phone or social media, so they are too small for those flaws to be seen. Though, they become pretty obvious when they get printed beyond A 4 format - Images taken with proper gear can be printed much bigger. I did billboards up to 6 meters wide...
So called filters are, technically, editing, but a photographer would usually chose a more subtle approach. We don't just squash a filter on top of an image, but work out details, contrasts, saturations etc. in certain parts of an image that needs adjustment.
Nothing you can do in an editing program is new. All the techniques and adjustments originate in the dark-room of the older days - this is also a widely ignored fact.
Below you see a raw file right out of the camera, and the edited version of the same image.
You see, the raw is a bit too dark, over all, and it lacks contrast.
This was taken in the afternoon, on a bright day, so the real light conditions were rather harsh. Hence I slightly under exposed during the shooting, to avoid the strong sun glare, but had to restore brightness in some parts of the image.
Cameras in general "see" different to the human eye. A camera is bound to its settings, over the whole picture, the human eye can adjust to the circumstances much faster.