Momentum
Momentum is the speed and strength of a price move — how forcefully price is travelling, regardless of direction.
Momentum building, then fading
Momentum measures the rate of change of price rather than its level. Strong momentum means a move is powerful and likely to continue; fading momentum warns that a trend is running out of energy even if price is still rising or falling.
Momentum indicators like RSI and MACD exist to quantify this. They are most useful as a confirmation layer — momentum agreeing with trend is a higher-probability setup than either alone.