What is "Northbridge" ?

Bridge protocol of KillSwitch.Finance
Northbridge is a bridge protocol that allows users to bridge back and forth between chains/networks. Currently available chains include Binance Smart Chain, Ethereum, BitKub Chain, Polygon(MATIC), KuCoinChain and REI chain. KillSwitch has designed a system where farmers transfer through a Bridge similar to an original chain.
Bridge — Original Chain
It’s working principle is to “Lock Token” in a Smart Contract and “Mint” out the tokens from the other side of another Chain. Once the action of transferring back, the bridge will “Burn” the tokens and “Unlock” the tokens that were locked.
For Example:
If users want to transfer MATIC from Polygon chain to BSC through Northbridge, they will need to use MATIC to bridge, users will then receive kMATIC tokens from BSC in which Northbridge will “Lock” MATIC token then “Mint” kMATIC to BSC. Users can also exchange kMATIC tokens with any other type of token through
Vice Versa, if you want to “Bridge” kMATIC (from BSC) back to the Polygon chain, the system will “Burn” kMATIC and unlock MATIC to transfer to your wallet.
Click for more information: Medium