what is black swan?

I just watched requiem for a dream and i am intrested in black swan by the same director. I watched the trailer cause darren aronofsky's movies are known to be hardcore but i didn't get anything. can someone tell me what it is about?
thank you

Its been a good decade since I saw in theatres, but I’ll recap from memory.*
It’s a psychological look into the high demands of ballet that leads to a harrowing descent into madness as she copes with the pressures set upon her.

^^This. And Portman's performance. Carries the movie alone!

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It's about 108 minutes long.

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"Film is a disease. When it infects your bloodstream it takes over as the number one hormone. It bosses the enzymes, directs the pineal gland, plays Iago to your psyche. As with heroin, the antidote to Film is more Film." - Frank Capra