$BTC (Bitcoin) and USD (U.S. Dollar) represent two very different forms of currency. $BTC is a decentralized digital asset operating on a blockchain, free from central banks, while the USD is a fiat currency issued and regulated by the U.S. government. The BTC/USD trading pair is a popular way to measure Bitcoin's value in traditional terms. Bitcoin's price often fluctuates due to supply-demand dynamics, market sentiment, macroeconomic news, and regulatory developments. Investors view Bitcoin as both a speculative asset and a hedge against inflation, whereas the USD remains the world’s dominant reserve currency. Their interaction defines a major segment of global finance.