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A perp is a contract that follows an asset's price and never expires. Long if you think it goes up, short if down. You don't hold the asset, only the position.
88 markets: BTC, ETH, SOL and other crypto, NVDA, AAPL, TSLA, the S&P 500 and Nasdaq, gold, silver and oil. All of them trade 24/7, even when the stock exchange is closed.