What do you see out of your elbow? It’s a bit like that

Close and cover your other eye and look around. After a while your brain realises that your covered eye doesn't produce any important information and focuses on the stuff you can see. After a longer time you don't even realise that you were supposed to have two eyes unless you specifically decide to focus to what is going on in your covered eye.

Other example: look at something in front of you and try to find the edge of your vision with your index finger. Keep looking forward while you move your finger in and out from your vision. The finger disappears, but not into darkness but into...void? Nothingness? Extend that over your whole vision and you get what blind people see.

Or imagine you were supposed to have 360 vision but due your vision loss you can only see around ~~200~~ 180 degrees (100-110 degrees in each eye) and even that last bit in each eye is barely visible. Now your friend asks you to describe what you see behind your back. What do you answer? Is it dark? Black? Is it anything?

I am pretty sure there are many definitions of legally blind and it is not like they see nothing. Usually cues like light and shadows are perceived while some might see colours up close.

Still closing an eye like others have mentioned is I think the closest one can imagine or viewing outside from a super foggy glass.

Also the course the blindness and reasons may cause a big difference if there is any expected visually sensory from brain. Many people are not born blind and become blind; with those who were born blind I can imagine the brain just starts ignoring any visually input from eye and then there nothing can be really nothing as in not existence of it.

There are hundreds of different types of blindness but most of it comes down to perception, if you were born without vision at all then you don’t have a concept of black or color or visual shape so it’s just not there.

It depends on the person. I used to be able to see fine. If you imagine what you see when you rub your eyes too hard (don't try it!) see get red and green swirls, just imagine that, only so solid you can't see through it, with occasional bright bits.

It's one of those things you don't really notice until someone mentions it, so thanks for that.

Don't think about breathing! Ha got you.

It’s common to say that there’s a spectrum of vision, but that implies a one-dimensional series of transitions from full sight to no sight, and that doesn’t capture the variety.

Some people have spotty vision. Others center vision, but no peripheral vision. Yet others peripheral but no center vision.

Cloudy vision, blurry vision, light perception only, total blindness, vision that varies through the day, double vision, eyes that move uncontrollably in any of many ways, obstructed vision, extreme nearsightedness, etc., etc., etc.

In short: imagine something about the human visual system that could vary, and then assume that variation is present in a goodly number of people.

As far as trying to fathom blindness:

How would you describe your ability to catch yummy flying bacon (okay, actually mosquitos) using only echolocation by clicking your tongue?

(Side note: most bats have great vision. Some have this awesome additional sense. Jealous?)

It’s hard to fathom someone else’s sensory experience. I’m sighted but my eyes aren’t straight and my vision isn’t fused (not one picture), meaning I have fewer depth cues than you probably do. To describe the condition I usually have to dispel some myths—yes, I have depth perception, it’s just impaired in some ways. I can’t watch 3D movies, but wow, not missing much there.

So I can describe my experience to you, and I have some sense of how you see the world, but that’s about as far as it goes. I could rig up some weird augmented reality experience to present the world to you kinda like I see it, but that would just be a taste, not the everyday experience.

There’s not that much difference between my vision and yours (probably); now imagine a greater difference and you start to get a sense of the spectrum. And then, after a few minutes of this talk, life moves on, we have coffee and talk about movies or books and make jokes.

The similarities are far greater than the differences, BUT there are problems with the built world not being as accessible as it should be. That’s a whole ‘nother discussion.

It’s not black or darkness for me. I have several blind spots in my vision and I would describe them as solid gray.

It’s like her deaf person doesn’t hear silence because they have never known hearing at all. It’s an absence. You can’t understand darkness without first seeing light so it’s meaningless.

For me, it is like my eyes were never plugged in.

Yeah Same bro.