One of the general requirements of writing is research. When talking about places, landscapes, buildings, and so forth, you want your reader to feel like they are there. the only way to do that is for you, the author, to have that same feeling.
If you are writing about a modern day house, that probably is not too hard to imagine. But what if you are writing about a place that you have never been? Perhaps your protagonist lives in a castle, or they are travelling to a country that you have never been to? How do you make these locations real?
The answer is research. My current story takes place in Egypt, just outside of Giza. In addition, it takes place over a hundred years ago. Being that I have never been to Egypt, and will never be there a hundred years ago, I needed to do a lot of research to get a feel for the area. Much of my digging revolved around old photographs and paintings. Paintings have an advantage as they are in color, whereas photos of the time were in black and white. I spent hours going through images, reading websites, and so forth. Interestingly, those hours have amounted to about two paragraphs in my current work. That might seem like a small payoff, but to set the scene is, to help transport the reader to that time and place is something I value greatly.
Another tool that is very helpful is Google maps. Maps in general show you where things are (obviously) but I got a new appreciation for the area by using Streetview. My first book was set in London (another place I haven't been) and I took a kind of virtual tour via using streetview. I 'walked' around London, the Thames, alleys, all the places that made up locations for my story. It is not a substitute for actually being there, but it was incredibly helpful.
There are many other reasons for research, but I thought I would take a few minutes and share what I have been doing currently and how it has helped me.