Shooting with Available Light
In its purest form, available light photography includes only natural lighting, with no modifications by the photographer. While this doesn't provide the photographer with too much control over the lighting other than deciding what time of day to shoot and whether to stand in the sun or in the shade, natural lighting can still be absolutely exquisite to work with.
Available light photography is best practiced outdoors during the daytime, as relatively little natural light filters indoors, and shooting by night is quite technically difficult (though by no means impossible.)
Diffuse lighting effects is best provided on cloudy days, in the shade where there is no direct sunlight, which tend to create softer effects, or just before and after dawn and dusk respectively where you also have beautiful colorplay. Higher contrast lighting, on the other hand, is readily found on bright sunny days, as well as sparkles and shimmers of lightplay in the surrounding environment.
The lack of control of the photographer may force them to take steps that may feel technically wrong, for instance, leaving the background overexposed so that the subject is properly exposed. While this may bother some photographers, and not provide as much control over the final product, it's also an opportunity for artistic license, to play on nature's unpredictability and see how you can turn it to your advantage. Such photography is inherently innovation, and in the digital age where countless millions of photos by aspiring photographers are uploaded every day, such experimentation is necessary to stand out.