How does ISIS “claim responsibility”?

Has anyone ever wondered how ISIS claims responsibility for bombs and whatever else around the globe? It’s not an official group. There’s no headquarters. There’s no president. There’s no spokesman. There’s no public relations firm. And if there were these things, you’d think they’d be bombed. Bombed by Russia that is.

But anytime there’s some bomb in Afghanistan or car ramming in Europe, mainstream media is quick to tell everyone that “ISIS has claimed responsibility.”

But…HOW did “ISIS” claim responsibility? And WHO claimed responsibility on behalf of ISIS? Who is authorized to speak on behalf on ISIS around the globe? Why is the name of the person who claimed responsibility for ISIS ever released by the mainstream media?

Since Langley and the CIA operate ISIS, does someone from the CIA call up CNN to “claim responsibility”?

I imagine Joe from the CIA over at Langley calls up CNN and says “hey, tell them we claim responsibility” and then the CNN clowns say “ISIS has claimed responsibility for the bomb attack this morning” leaving out, you know, some crucial details. I imagine the CIA have special direct access lines to the mainstream media outlets to “claim responsibility” on behalf of  their pet project “ISIS”.

Does anyone ever notice how they never say WHO or HOW “ISIS” claims responsibility?