P&L, maker and taker fees, slippage, liquidity and volume

After you trade, you need to measure how you are doing and understand what it cost. These terms appear on almost every trading screen.

P&L means profit and loss. Unrealized P&L is the gain or loss on a position you still hold. It changes with every price move and is only on paper. Realized P&L is the gain or loss locked in when you sell (or close) the position.