Sounds like a simple question, but I suspect that the answer can sometimes be quite complex. I'll tell you why I take photos.
The main reason is communication. It is a way for me to show people what I see. In my case it is showing real things, usually nature, and the attempt is to show those things as they really are. In turn that makes me slow down and really look at what I am photographing, and then read up on what it is, and get in contact with experts in that field.

And then there is the how.
Reality comes in many shades and it is far too complex to show in a simple photograph. For a start, we live in time and a still photo is, well, still. And the camera is imperfect and gives a representation of reality, not reality itself and it is a slightly different reality than our eyes show us. So I have to make decisions as to what shade of reality I show.

There are some things that a camera will do that our eyes cannot. For example: slow shutter speeds allowing the blurring of some components to a greater or lesser extent. Our eyes almost always blur to the same extent.
And some things that a camera can't do that our eyes/brain can. Cameras are limited to about 4,000 times the brightness form the darkest to the lightest pixel. Our eyes/brain can "see" scenes with up to 1,000,000 times. Actually our eyes can only can only measure light differences with a factor of 10 difference between adjacent pixels but our brains can construct the rest by combining images (sort of an in house HDR).
Then there is the way our brain interprets things. Some things that we can easily ignore in a moving scene becomes very obvious in a photo. A gorilla walking across a basketball court may be virtually invisible in a moving picture, but isn't in a still photo https://www.youtube.com/watch?v=IGQmdoK_ZfY . Power lines often aren't a worry in a real scene, but can become intolerable in a still photo. We have to allow for things like this as we compose a photo and that is a challenge, and that becomes part of the attraction as we learn more of how to do it. It becomes an art, even when the aim is for reality. I seem to remember some comment that taking pictures of reality isn't art. I don't agree with that.

Then there are the choices of which reality I choose to show. Perhaps that involves decisions as to what time of day, what lighting, what angle, what instant, what camera, what lens, what settings, etc, etc. There are often almost infinite ways in which a photo of any one thing can be taken and again that is a challenge and a lot of fun. Of course it helps to know what your objective is.