When you’re shooting in situations where there is a big difference between the light and dark areas, your camera will expose for the light — unless you manually control the exposure — and that means the shadows will be too dark. This happens all the time when you shoot into the light, like a sunset or a photo in front of a window, but often those photos can turn out great with the proper technique.
The way to get great photos in those situations is to use HDR (high dynamic resolution) photography. You can either shoot several exposures with your expensive digital camera and then merge them later using computer software, like Photomatix, or turn the HDR setting on for your camera phone, if it has it.
Basically the camera shoots three different exposures. One over exposed, one normal and one under exposed. Then, it takes the best parts of each exposure and merges them into the final image. The camera shoots all three images in a fraction of a second but it’s best to use a tripod for HDR photos.
Newer iPhones and Android phones have an HDR setting in the native camera app but if your phone doesn’t have it, there are third party apps you can use.
The HDR setting built into your camera phone is adequate but doesn’t allow for any adjustments so I recommend using a third party HDR app. For iPhones I recommend Pro HDR X and for Android I think HDR Camera is the best.
Often, you can fix you camera phone photos that didn’t come out the way you hoped by using the HDR Scape filter in the Snapseed app.