The Eyes Have It!
Controversy abounds as to the actual numbers, but the fact is that your eyes can see much better that your camera. Dynamic range in photography describes the ratio between the maximum and minimum measurable light intensities. Your eyes can see a higher range (more stops) of light and dark than a camera can. Part of this difference is because your eyes are constantly adjusting to the scene, and in part because your eyes are connected to a brain that can make assumptions and "fill in" some of the missing information. I will leave discussion of the exact numbers of stops for the experts to argue. It is not important. Just know that every time you take a photo, especially at night you are making a compromise. What you see and what the camera sees are not the same. You have to work within this compromise, or you can advance to bracket exposures, shooting RAW files, and more robust photo editing software. For now lets have some fun. Cameras are getting better all the time, but they still see a smaller range of light to dark then your eyes can. By shooting several exposures you can get the range you need for the best image.
What It Means to You
Cameras need light to see just like our eyes. While our eyes adjust quickly and automatically scene to scene, you must adjust your camera so it sees what you do. This is even more true after dark. Even then a little photo editing can help tweak out some details and adjust colors.
Below are some graphics which show how a camera sees light. Print a copy and put it in your camera bag. We will discuss exposure settings as we go, and this will be a handy guide.
What it Means
The backgrounds show that the image will get darker or lighter as you make adjustments. Watch the gradient. For fun you can try the Digital Camera Simulator.