USDT, also known as Tether, is the stablecoin with the highest market capitalization, backed by US dollar. The primary purpose of USDT is to provide stability in the volatile crypto market. Unlike other cryptocurrencies like Bitcoin or Ethereum, which have prices that fluctuate wildly, one USDT token is designed to remain exactly equal to one USD. This is achieved by maintaining a reserve of real-world assets, including cash and equivalents, which back each token issued.

Tether was launched in 2014 and played a crucial role in the cryptocurrency ecosystem. It provides a 'safe haven' during market volatility, allows for quick transactions (especially cross-border), and opens the door to a host of financial applications. It's often used as a reference in trading pairs on crypto exchanges due to its stability.

In 2023, with the events of USDC losing peg and Paxos was ordered by the SEC to cease issuing new BUSD,  the market value of the whole stablecoins has declined. However, the market value of USDT continues to rise, maintaining its position as the “Number one stablecoin".

Above are only for introduction, not intended as investment advice.