Tick

A tick is the smallest unit of price change. In forex, a tick on a 5-decimal quote is 0.00001 — one pipette. On futures contracts (like the E-mini S&P 500), a tick is 0.25 index points worth $12.50 per contract. On indices CFDs, tick size varies by broker. Tick is a market-microstructure concept. It tells you how granularly the market updates. In a fast-moving major like EUR/USD during London open, you might see 200+ ticks per second. In a quiet exotic at 3am, you might see 1 tick every 30 seconds. Tick frequency is a proxy for liquidity. Traders care about ticks for two reasons: (1) the smaller the tick size, the tighter the spread can be, and (2) tick charts (which print a candle every N ticks rather than every N seconds) are popular with scalpers because they normalize for activity rather than time.