Parachains are complete and independent blockchains that can have their own tokens and tools for specific tasks. They will be created by third-party developers and attached to the general Polkadot network.
Parathreads are parallel blockchains that are similar in technology to parachains. But they are different in that they can be rented instantly and for any period of time.
Bridges are also similar to parachains. But their main (and actually only) task is to connect the Polkadot ecosystem with third-party blockchains. For example, Bitcoin, Ethereum, Binance Chain, and others.
Through parachain auctions, DOT token holders can vote for their favorite projects, and the development team, in turn, receives the necessary funds to lease a slot on the main Relay Chain network.
At the end of these auctions, one of two results can be obtained:
If the team fails to raise enough contributions, all tokens will be returned to participants after the auction, and the parachain will not be launched on the Polkadot system.
If the project does raise enough money to win the auction, then DOT tokens will only be returned to contributors at the end of the parachain slot rental period.
This auction system provides maximum security for investors, as they will get their tokens back in any case. And if the project they voted for is successful enough, investors will receive valuable parachain tokens along with their DOTs (as a reward for providing a temporary loan to the developers).
