What is the Proof of Burn (PoB) consensus protocol?

Proof of Burn (PoB) is a protocol where miners get the right to add a block based on the number of tokens burned. Tokens must be sent to the “burner” address, after which they cannot be restored. The more tokens were burned, the higher the chance of being selected. This mechanism is associated with the loss of short-term wealth with the ability to gain permanent privileges to add new blocks, which stimulates the long-term commitment of miners. The PoB protocol is used by such cryptocurrencies as Factom (FCT), Counterparty (XCP), and Slimcoin (SLM).