Bancor is an decentralized network of on-chain automated market makers (AMMs) on Ethereum, Solana, xDai and Energi, supporting instant, low-cost trading, as well as Single-Sided Staking and 100% Impermanent Loss Protection for any listed token.

Bancor is a decentralized exchange (DEX) built on the Ethereum. The Bancor protocol employs an automated market maker (AMM) smart contract to facilitate token trades against token liquidity pools without matching buyers and sellers. It has a built-in token called BNT that serves as the common price token to fulfill trades among other smart contract tokens. A portion of total trading fees are distributed to Liquidity Providers, or LPs, that deposit tokens into Liquidity Pools. Trading fees also protect user deposits from Impermanent Loss while minted and burned BNT supply maintains the constant market function for continuous token pricing. 
The BNT token is the common price token that facilitates trades within the Bancor exchange. Instead of a central order book, Bancor fulfills trades between users and cryptoasset reserves called liquidity pools. Tokens in a liquidity pool are matched with a proportionate BNT amount to create pairs. The BNT serves as a common price among all unique tokens which creates markets for two otherwise illiquid tokens.

Fixed Reserve Ratio The BNT smart contract controls BNT supply in proportion to each token according to its Fixed Reserve Ratio, or FRR. The FRR remains constant to ensure the token price in BNT reflects supply and demand on the Bancor exchange. When a given token is purchased from the exchange, the paired BNT amount is burned from the supply to maintain the FRR. When the exchange receives a new token, new BNT is minted to maintain the FRR. The BancorDAO determines and documents the FRR so token prices are continuously and transparently updated.

LP Fees Liquidity pools are created by liquidity provider, or LP deposits. These deposits accrue trading fees to the LP according to their share of the pool's total liquidity. Users pay trading fees as a percentage of their trade value. While the user pays fees in the traded token, the protocol converts the fee into a proportionate amount of the traded token and its BNT pair. Trading fees are then distributed to LPs in either the traded token or BNT according to the asset they deposited in the pool.

Elastic Supply Bancor V2.1 made BNT supply elastic. Previously, BNT supply changed only when tokens were traded on the exchange. Deposits from LPs into liquidity pools required a proportionate amount of the token and BNT. Now, LPs can make single-sided deposits, and the BNT smart contract mints or burns BNT according to the FRR. Additionally, BNT is burned when an LP adds BNT to any pool. This burn function is designed to put deflationary pressure on BNT supply as asset values increase.

Each trade results in at least two transactions, a debit and a credit of the traded tokens into their respective liquidity pools. Bancor's AMM adjusts the BNT supply in each token's liquidity pool to maintain the pair's price according to the Fixed Reserve Rate, or FRR. For tokens credited into a liquidity pool, new BNT is minted and stored in the pool. When tokens are debited, matching BNT tokens are burned, or permanently removed from the total BNT supply.

If a user provides an asset to a pool, they create no debit transaction. In this case, BNT supply grows with the new BNT minted into the liquidity pool. If a user later supplies BNT to the same pool, the protocol burns the same amount of BNT from the pool to maintain the supply of BNT according to the AMM algorithm.

Connector Weight Token prices on the Bancor exchange adjust according to Bancor's AMM algorithm. A token's price is a function of the total supply relative to the BNT supply and price-weighted by a Connector Weight, or CW, factor. Holders of BNT decide the CW that determines how sensitively the token's price adjusts as its supply changes within the Bancor protocol. Bancor V2.1 introduced new functionality that adjusts BNT supply relative to a token's supply, according to the CW algorithm. This new provision eliminated the requirement for traders and LPs to convert a proportionate amount of their transaction tokens into BNT.