Moving Average
Also called: SMA, EMA, exponential moving average, 50-day moving average
A moving average smooths price by averaging the last N periods, filtering noise to reveal direction. Simple averages weight every period equally; exponential ones weight recent data more heavily and therefore turn faster. Every moving average lags by construction — it is describing where price has been — which is why they work in trends and whipsaw badly in ranges.
Formula
SMA = Sum of last N closing prices ÷ N