One of the key reasons for Binance's success is its wide range of trading pairs. Binance offers over 500 trading pairs, including fiat-to-crypto pairs, which makes it easy for users to buy and sell cryptocurrencies. This has helped to attract new investors to the market and increase liquidity.

Binance also has a user-friendly interface and offers a range of trading options, including spot trading, margin trading, and futures trading. This allows users to choose the trading option that best suits their needs and level of experience.

Another factor that sets Binance apart from other exchanges is its low fees. Binance charges a flat fee of 0.1% per trade, which is significantly lower than many other exchanges. Additionally, users can receive further discounts on fees by holding Binance's native cryptocurrency, Binance Coin (BNB).

Binance has also been at the forefront of innovation in the cryptocurrency industry. In 2019, Binance launched its own blockchain network, Binance Chain, which allows for faster and cheaper transactions. Binance has also launched numerous other products and services, including a decentralized exchange (Binance DEX), a cryptocurrency wallet (Binance Wallet), and a staking platform (Binance Staking).

Finally, Binance has a strong reputation for security. It has never been hacked, and it takes extensive measures to protect user funds and data. Binance also offers two-factor authentication (2FA) and other security features to help users protect their accounts.

In conclusion, Binance has become the leading cryptocurrency exchange in 2021 due to its wide range of trading pairs, user-friendly interface, low fees, innovation, and strong security measures. As the cryptocurrency industry continues to grow and evolve, Binance is well-positioned to remain a major player in the market.