exposure compensation:

Exposure compensation basically helps you override automatic exposure adjustments your camera makes in situations with uneven light distribution, filters, non-standard processing, or underexposure or overexposure. It lets you take control of your image’s brightness by manually increasing or decreasing exposure.

exposure bracketing

when you bracket your shots you take exactly the same picture of your subject at several different exposures. This technique gives you a range of options to choose from when you’re editing. As a result, it’s much less likely that you’ll end up with a badly underexposed or overexposed photo.

HDR photos

HDR (high dynamic range) helps you get great shots in high-contrast situations. The iPhone camera takes several photos in rapid succession at different exposures and blends them together to bring more highlight and shadow detail to your photos.