A wedge is bounded by two converging trend lines that both slope the same way. Unlike a triangle, both lines tilt in one direction — and the twist is that wedges typically break against their slope. They show a trend running out of room as each push makes less progress.
Rising wedge (bearish)
Both lines slope up but converge, with each higher high weaker than the last. Price is grinding upward on fading momentum, and the typical resolution is a break downward. Rising wedges often appear at the end of an uptrend or as a bearish continuation in a downtrend's bounce.
Falling wedge (bullish)
The mirror: both lines slope down and converge, each lower low losing momentum, and the typical resolution is a break upward. Falling wedges often mark the end of a pullback or downtrend. In both cases the break — on volume — is the trigger, not the wedge shape itself.
Caution
Wedges are easy to over-draw — it is tempting to force converging lines onto noise. Require clean touches on both lines (at least two or three each) and wait for the break to confirm. A wedge that 'breaks the wrong way' is common enough that the break, not the bias, is what you trade.