Just realized a lot of people trading crypto don't really understand what is pnl, and honestly it's wild because it's literally the foundation of knowing if you're making money or losing it.

So here's the thing - pnl just means profit and loss, but in crypto it's way more nuanced than most people think. You've got realized pnl (money you actually locked in by closing a position) and unrealized pnl (gains or losses still sitting in open trades). They work totally differently and people mix them up all the time.

Let me break down what is pnl with a simple example. Say you bought some ETH at $1,900 and it's trading at $1,600 right now. You haven't sold yet, so you've got $300 in unrealized losses. But if you actually sold at $1,600, that $300 loss becomes realized. The mark-to-market (MTM) price is what matters for tracking this - it's basically the current market price of whatever you're holding.

There's also this concept called future value that trips people up. If you stake $1,000 worth of crypto at 4% yearly returns, you'll have $1,040 in a year. That $1,040 is your future value. It helps you understand what your holdings could be worth down the line.

Now, if you're doing multiple trades, calculating pnl gets more complex. You could use FIFO (first-in, first-out), LIFO (last-in, first-out), or weighted average cost method - each gives different results depending on which units you're selling. For instance, if Bob bought 1 BTC at $1,100, then bought another at $800, and sold one at $1,200, using FIFO gives him $100 profit, but LIFO would show $400 profit because it assumes he sold the most recent purchase.

For perpetual contracts, you need to calculate both realized and unrealized pnl and add them together. Most people forget about trading fees and funding rates, which eat into your actual returns pretty hard.

Honestly, understanding what is pnl properly changed how I approach trading. You start realizing your portfolio performance way better, and you can actually assess if your strategy is working or just lucky. Tools like spreadsheets or trading bots help, but the real move is just knowing these fundamentals yourself. Makes a massive difference when you're making decisions on your next trades.