Polkadot (DOT) tries to solve two problems: scalability and interoperability of blockchains.
Scalability is solved with the sharding technique (the blockchain is divided into many smaller fragments coordinated by a central blockchain, this increases the speed of transactions without compromising decentralization). Interoperability tries to combine multiple different blochchains (each specializing in a certain task).
Pokadot succeeds in this thanks to its modular architecture, consisting of:
-Relay Chain (central module linked to the Dot token. What is it for? For governance and to guarantee security thanks to a Proof Of Stake system. Furthermore, the relay chain coordinates interoperability between the various chains: the internal ones, called Parachains, and, those external to Polkadot like Ethereum)
-Parachains (these are the blockchains developed on Polkadot, each with its own token. These then, thanks to the Relay Chain, bind to the others on Polkadot and to external ones. How can I create Parachains? Through bonding: I have to bind Dot tokens)
-Bridges (they are blockchains with their own token that connect the Polkadot ecosystem with external blockchains: Ethereum, BTC, Binance, etc)
Regarding the consent we have:
-Nominators (these are nodes possessing the dot token and electing validators)
-Validators (validate transactions and locks; validators also stack)
-Collators (they retrieve all the transactions scattered in the blockchain that due to the sharding is fragmented into many small pieces; then they process the transactions and pass them to the validators)
-Fishermen (we could define them as the police: they control the ecosystem so if the nodes work well; if there are nodes that behave badly, they report to the nominators and the punishments that can lead to the total loss of all the dot tokens placed in stackig)
Several projects have already been created: Edgeware (useful for smart contracts on Polkadot and on external systems), ChainX (multiasset management protocol), Spechle Os (to create your own identity on Polkadot), Darwinia Network (interoperability with Ethereum and DeFi )
For more info: Polkadot Network
