A photographer’s job is working with lights and an appreciation of how to use what’s available will make a huge difference. However there are times when natural lights are place behind the subject. And this situation we need to use fill flash.
Another option with this kind of shoot, is to use a silver, gold or white reflector.
Backlift subject often require fill in flash to make sure their faces aren’t obscured in shadow. An off-camera flash gives you added flexibility.