"In Hinduism, Kali Yuga is the last of the four stages the world goes through as part of a 'cycle of yugas' described in the Sanskrit scriptures.
The other ages are called Satya Yuga, Treta Yuga, and Dvapara Yuga"
But what else do we know about it?
Well in short kali was a demon who appeared in the End of Dwapara-yuga where he was stopped by King Parikshit & later he asked him for the place to live,
then king Parikshit gave him 5 places to get dwell into, the places like terracotta in which the wines were kept, places where the low character women lived, Places where people gamble & in Gold.
If you have read Mahabharata, then you might have known that the vanishing of Dharma was started since then.
Greed, pride, etc everything existed, kali here is nothing but a STATE OF MIND, this refers in a Negative state,
every person had this quality in the mythic age as of in today's age the only good thing were The God's had resided with the Humans they used to be with them & show them the ways to do so.
Kali-yuga is where an Individual starts to greed, has pride for his work, has a rapacity of their belongings. Here this State of Mind creates a Demon itself which is called Kali.