Fly

True flies are insects of the order Diptera (from the Greek di = two, and ptera = wings). The most obvious distinction from other orders of insects is that a typical fly possesses a pair of flight wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax. (Some species of flies are exceptional in that they are secondarily flightless.) The only other order of insects bearing two true, functional wings plus any form of halteres are the Strepsiptera, and in contrast to the flies, the Strepsiptera bear their halteres on the mesothorax and their flight wings on the metathorax.

Taxonomy

The presence of a single pair of wings distinguishes most true flies from other insects with "fly" in their names, such as mayflies, dragonflies, damselflies, stoneflies, whiteflies, fireflies, alderflies, dobsonflies, snakeflies, sawflies, caddisflies, butterflies, or scorpionflies. However, some true flies have become secondarily wingless, for example many members of the superfamily Hippoboscoidea and some species that are inquilines in social insect colonies.

Revolution

A revolution (from the Latin revolutio, "a turn around") is a fundamental change in political power or organizational structures that takes place in a relatively short period of time when the population rises up in revolt against the current authorities. Aristotle described two types of political revolution:

Revolutions have occurred through human history and vary widely in terms of methods, duration, and motivating ideology. Their results include major changes in culture, economy, and socio-political institutions.

Scholarly debates about what does and does not constitute a revolution center on several issues. Early studies of revolutions primarily analyzed events in European history from a psychological perspective, but more modern examinations include global events and incorporate perspectives from several social sciences, including sociology and political science. Several generations of scholarly thought on revolutions have generated many competing theories and contributed much to the current understanding of this complex phenomenon.