A truss bridge is a bridge that bears its weight through its truss system. This truss system is composed of triangles that give its strength.
Truss bridges are one of the oldest types of modern bridges and are more economical to build than solid beams with additional support structures on the bottom.
Most commonly used truss bridge designs are Pratt, Warren, and Howe, but engineers have used many different truss patterns in bridges.
Cantilever bridges are beam bridges that are supported on only one end. These type of bridges often use a pair of spans that extend from opposite sides of the supporting structures to and meet in the middle. This bridge feature allows ships and other superstructures to pass.
Truss bridges can be made with all kinds of materials. The most impressive ones I've seen so far are the bridges made with popsicle sticks and glue; however, I try to minimize the mess in classrooms, so my truss bridges are made with foam cubes and straws.
Have a great day.