This document discusses different types and causes of human migration. It outlines Ravenstein's laws from the 1870s which found that most migration occurs over short distances, in a step-by-step rural to urban fashion. Economic, political, environmental, cultural, technological, and information factors can all catalyze migration by either pushing people away from or pulling people towards certain locations. Voluntary migration involves an element of choice while forced migration removes that choice, as seen in events like the Trail of Tears.