Short answers, pulled from the story.
The earliest states emerged in the fertile valleys of Mesopotamia and Egypt to protect stored grain from looters and raiders. These societies developed hierarchical structures and a ruling elite to organize defense and collect taxes. This need for protection created the first states as essentially protection rackets with a monopoly on physical force.
The word state derives from the Latin word status meaning condition or circumstances and ultimately from stare meaning to stand or remain. The term was revived in 14th-century Europe alongside Roman law to describe the legal standing of persons and the special status of the king. By the early 16th century the works of Niccolò Machiavelli popularized the word in its modern sense separating the state from the church.
Charles Tilly argued that states are essentially organized crime syndicates that sell protection from themselves and that states are created by war. In Europe states appeared around 990 but became particularly prominent after 1490. The process involved war making to eliminate outside rivals and state making to eliminate rivals inside the territory.
Max Weber identified three main sources of political legitimacy as traditional grounds charismatic leadership and rational-legal authority. The modern state is characterized primarily by appeals to rational-legal authority where legitimacy is derived from the belief that a certain group has been placed in power in a legal manner. This shift from divine right to rational-legal authority marked a fundamental change in how states justified their power over their subjects.
Anarchists regard the state and hierarchies as unnecessary and harmful promoting a stateless society based on voluntary cooperative institutions. Marxist theorists including Karl Marx and Friedrich Engels viewed the state as a partisan instrument that primarily serves the interests of the upper class. They believed that the state would wither away in a classless society replaced only by the administration of things.
State failure occurs when sovereignty over claimed territory has collapsed or was never effectively at all due to weak or non-existent institutions. European colonization defined many arbitrary borders that mixed different cultural groups under the same national identities making it difficult to build states with legitimacy among all the population. Many of these states emerged from colonization in a state of poverty and with institutions designed to extract natural resources.