Dynamic range in photography is the difference between the brightest and darkest part of a scene that a camera sensor can capture. Let's keep it simple silly as the whole purpose of this post is beginner focused. The dynamic range of a given camera sensor becomes important when the photo has a major difference between the dark and bright parts.

Example: A room with a window during the daytime. When trying to take an indoor space shot, it would be super hard for the camera to capture everything in one shot. Digital cameras don't see the way human eyes do. Due to this limitation, the indoor will appear to be very dark when the exposure settings are dialled for the window. Try dialling the settings for indoor exposure, this time windows will get overexposed and turn white. In order to solve this problem and produce a photo with maximum details, HDR photography technique is needed.