Why are impact sockets always black in color, and regular sockets always chrome-plated and shiny?

GOOD, Impact sockets are made from case-hardened steel!

The black is gun blueing. Maybe the steel is harder than chrome?

The color doesn't make them any stronger, but it does make it easier to tell them apart from standard sockets.

The black color doesn't make them stronger, it just makes identification easier, since impact sockets are thicker than normal sockets.

As all say, it is for identification. Impact sockets are not only thicker but are less brittle. If they break they just split or crack, while standard sockets can explode under impact with enough force to blind you.

the black is the scab on the socket, it might bleed if it gets taken off, torn or ruptured with hard food and then it will form again

not sapose to be perty just impack pruf . you can look perty with your crome ones