Variety of trusses exist because they all have different characteristics and different purposes. For example, there are the king post trusses, fink trusses, howe, pratt, and scissors trusses. As you can see from the illustration below, all of them have entirely different shape. Furthermore, king post trusses are among the simplest and they have one vertical support which connects the two angled supports.
Variety of Trusses and their Characteristics
If you are interested in this topic and you need to learn more details, see the pictures and the explanations on the pictures below. Also, click the link at the end of the post.