Took this photo back in September, but only got around to finish processing it now.
This nebula is a reflection nebula, which means it does not “glow” by its own, but is lit up from one or more bright stars from the inside of the nebula.
While being located roughly 4000 light years away, the central star which lights it up, is estimated to be only roughly 100'000 years old, which is really young in stellar terms. It spans over 12 arcminutes in the night sky, which at the distance of 4000 light years, gives it a size of 15 light years across.
Since this nebula lays towrads the core of the milkyway (from earths perspective at least), the field of view is filled with hundreds of stars!
Around the Cocoon Nebula parts of the ISM (Interstellar Medium) can be seen as dark dust clouds. ISM is basically dust, that does not emit light and is not lit up by any star or similar object. Thus it can only be seen as clouds of dark dust covering up other stars, making it impossible to see what is behind it (at least in the visual light spectrum).