What is experimental archaeology and how does it provide insight to the manufacture or construction of tools or architecture?

What is experimental archaeology and how does it provide insight to the manufacture or construction of tools or architecture? What are some experiments that have been conducted and what types of conclusions were drawn from these studies? If you could conduct an experiment in archaeology, what would you replicate or construct and how would you do it? Be sure to outline the step-by-step process for your selected method.