If they don't have any residual sight, they see absolutely nothing; no color or light.

Blindness is a spectrum though. Many people aren't totally blind.

Pulsating green and red patterns like if you rub your eyes too hard.

It's a bit like breathing, you forget about it until someone reminds you. So thanks for that!

(Kidding)

At the moment? Nothing in my left eye (always been that way) and currently in my right eye, I can see sorta normal. I can see light and dark and contrast. At the current moment, I can’t see colour (might change) and can’t distinguish details so I use VoiceOver on my tech. My vision might improve in the future as I’ve had surgeries this year, but it’s been through a lot of changes in the past.

I suppose it depends on whether you were born blind or not.

I lost my vision at five-years-old. So, I “see” things based on the colors and images that are still in my memories. I do the best I can to visualize things, with the help of descriptions from others; which vary in detail.
My dreams are in color, and mainly consist of visualizations I’ve come up with (one way or another) of people I know — and those I do not know. It can be rather vague, but the mind can come up with some interesting imagery on its own.

FOr instance, I know my credenza is made of a cherry wood. I’ve been looking to purchase a computer desk. And although I can’t see anymore, one of the considerations I have is that it would be nice to find a desk that matches the cherry wood aesthetic for the room.

Some blind (or visually impaired) people don’t care so much about matching. But, I do (to a certain extent).

I'm totally blind and its difficult to describe because I don't know what sight is. I was born blind but I do understand things like colors because I've been told things about colors like Fire is Red and the sun is Yellow. I also ask people when I am interested in knowing the color of an object or character in a game or cartoon.

Well I'll tell you what I don't see, an end to this coronavirus pandemic any time soon.
No but for real though, I see light and dark, like whether theres a light on or not. But aside from that, nothing else.

I have just light perception, I know how to face a light in a room, I know whether it's sunny or cloudy outside, but I see no shadows and have no use for colours.

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That depends on who you ask. People who were born blind have literally no concept of light and asking them what they see is like asking you what you see out of your elbow.

For people who lost their sight later in life, it depends on the individual and how they lost their sight.

I completely lost my sight in my left eye later in life, I see sparkles and fireworks on a dark background. It’s like what you would see if you rubbed your eyes really hard, except it doesn’t go away for me.

I still have some sighg in my right eye. I have large blind spots in the center and around the outer edges (that are basically sparkles that keep me from seeing) and the rest is kind of a blurry mess with occasional sparkles/black dots floating around.

I see a pasley pattern of deep purple/black that blossoms.

Not all people who are blind see nothing. I've got a little sight left, I can see light and the outlines of objects. To get it into perspective what it is that a fully blind person sees, try seeing from your elbow. Or your hand. That's right, you cant. Simple as that, unability to see anything or even attempt at doing so. Is that darkness or blackness? No, it's instead an absence of sensation.

I can see lights and outlines.

Someone who’s completely blind will see nothing.