It's a browser extension and mobile app that was built out of the need for a more secure crypto wallet. You can manage multiple accounts and it connects the users to different blockchains.
How to add Binance Smart Chain to MetaMask?
Setup your MetaMask account
Tap Networks and choose "Add Network"
Add the following information:
Network Name: Binance Smart Chain
New RPC URL: https://bsc-dataseed.binance.org/
ChainID: 56
Symbol: BNB
Block Explorer URL: https://bscscan.com
Save your work and you'll now be able to trade $BNB, $CASH and others
How to add CASH to MetaMask?
Login to your MetaMask account
Select "Binance Smart Chain" as your network
Select the "Assets" tab and tap "Add Token"
Paste the CASH contract address: 0xaa25a39d7aa8318e3EBC19d3678917B8Bd98A135
Select "Next" then "Add Token" and it will display your balance