Binance is a crypto exchange that started in the summer of 2017 and quickly became one of the largest in the world by trading volume, recording $200 million in profit in its second full quarter of operation. Binance Coin was launched as an ERC-20 token sold through an initial coin offering (ICO) to be used for discounted trading fees, of which a portion are burned each quarter. Once Binance launched Binance Chain, its own public blockchain in April 2019, the ERC-20 tokens were swapped for native tokens. On top of Binance Chain, the team built a decentralized exchange known as Binance DEX allowing traders to maintain custody of their funds. Over time, additional utility has been added to the token such as use in the Binance Launchpad lottery system and various payments in the Binance ecosystem. In addition, according to their CEO Changpeng Zhao ("CZ") 90% of Binance employees choose to receive part of their salary in BNB.
Binance Coin was originally launched as an ERC-20 token on Ethereum until April 2019. Binance converted all ERC-20 BNB tokens to Binance chain BNB coins a couple days after the Binance chain mainnet launched. Two months earlier, Binance chain’s testnet launched and was used by the internal Binance team and some high-volume traders for testing.
Binance’s decentralized exchange (DEX) is built on the Binance blockchain using Tendermint and the Cosmos Software Developer Kit (SDK). Binance forked Cosmos to create the Binance blockchain, which currently does not support smart contract features. Binance aims to use the Tendermint consensus framework to solve some interoperability problems with inter-blockchain communication (IBC).
Binance chain source code is currently not open source for competitiveness reasons, according to Binance. But the exchange plans to open source the DEX and blockchain codebases when both products gain more adoption.