Explain how imperialism has changed over time-from the early period of Spanish and Portuguese dominations, through the rise of the Atlantic system, to the new imperialism of the mid-to-late 19th century, up to the era of neo-colonization of the late 20th and 21th century. What are the main characteristics of each period? What changed over time? What did not change? In your opinion which system/era was easiest to resist and why?