CHIARASCURO as I’m sure you know is an Italian word, CHIARA (bright and clear) and SCURO (dark or obscure).
In photographic terms it’s usually taken to mean photographs taken in strong low sunlight where the highlights retain detail but the shadows are left well alone.
It’s perhaps fair to say that this style of photography can be at odds with the current emphasis on cameras which have a high dynamic range and where a lot of photographers try to pull out as much detail from the shadows when post processing. There is of course no such thing as a correct exposure so each to their own.
What I like about this style of photography is its’ ability to simplify compositions, isolate and highlight a particular subject in an urban environment. Conversely if one shows details in every part of the photo this can be visually confusing by giving equal importance to everything that’s there.
On a feelings level this style of photo can often give a sense of isolation and the potential loneliness of the urban world.
In terms of taking these type of photos a strong low directional light is critical; the winter or late in afternoon or early in the morning. In order to expose successfully you need to spot meter on the highlights in the scene or – as I do – overriding the evaluative meter reading and underexposing between 2 – 5 stops. Some increase in contrast when post processing can be useful as well. The style seems to often work best in black and white.