Triangles, and especially contracting triangles, can be clasified, if you want, into continuation and reversal patterns. Depending on which direction price breaks out of such a pattern, one can label the respective wave and in this way they can be an important tool in telling you where exactly price is in an, for example, impulsive move.
The most typical place for a triangle to appear is as a fourth wave consolidation. Price has the tendency to consolidate way more than it is traveling, and one of the most common forms of consolidation are the contracting triangles. Usually such a consolidation takes place as a fourth wave of an impulsive move, and in this case the contracting triangle is a continuation pattern, because price exits the pattern in the same direction it entered in the first place.
However, there are situations, and this is specifically valid for the non limiting contracting triangles, in which a such a triangle ends a complex form of correction (double or triple combinations) and in such a case it should be preceded by at least one more corrective form/pattern/structure, and the connection between the two to be made by an x wave. For more details about double and triple combinations please refer to the chapter dedicated to them as there are many examples being represented in there.
A triangle can be found also as being a part of a zig zag, and in this case it is taking the shape of a b wave, being as well a continuation pattern.
The recordings that come with this sub chapter will should you all the possible places a triangle can be found and how to interpret them in the broader context.