3/ 3. Hybrid Blockchains - A combination of public & private blockchain.
Eg - Banks are required to keep the ledgers publicly readable, but customers may demand privacy & control of sharing data of their accounts or wallets, hence a hybrid model is suitable.
1/ Did you know how many types of blockchains exist?
There are multiple criteria's to classify blockchain. The most common classifications are based on the permissions provided to the users & nodes to access, verify & update the blockchain.