In many medieval fantasy settings, and of course among park services and militaries today, the word "ranger" implies some kind of militant survivalist. But where did the term "rangers" actually come from, and what did they actually do?
Does the term "ranger" actually appear in any medieval texts, and was it a real profession outside of the Tolkien-esque fantasy connotations?
I wrote up a post on this a few months back .
Short version: in medieval England, 'forests' were specific defined areas with a different set of laws. The many government officials who enforced these laws and maintained the King's forests included, depending on which translation of the charter you read, 'regardatores', 'regarders', or 'rangers', tasked with inspecting forests.
The Rangers of modern militaries largely trace their lineage not to the game Warden type individuals mentioned already, but to 18th century ranging companies of colonial America.
Glenn Williams does a really good job of explaining the difference between regular soldiers, militia, rangers, scouts, and spies in his book "Dunmores War." Essentially the first ranging companies were established to "range" between forts on the frontier to make it more difficult for French or Native war parties to slip past undetected, thereby covering the area between the forts.
Some of these units were instead employed in a raiding/recon role, such as Rogers Rangers (His rules of ranging are still taught by modern US Army rangers to this day, and they consider themselves his successors) while others like Butler's Rangers were employed as an ultra-lite white raiding force that could keep up with British Native allies in the woods, and others still like John Graves Simcoe's Queen's Rangers functioned more as a combined arms light infantry legion that combined light infantry, light artillery, and horse to conduct conventional operations more rapidly. (Simcoe's journal describing their operations includes incredibly little about traditional "ranging" or direct recon, or long range raiding that the OGs like Rogers got up to during the French & Indian war.)
Finally we can find examples of units like the Connaught Rangers that had the word in their name, but functioned like most other infantry units.
With the exception of the Connaught Rangers, what all the others have in common is fighting as skirmishers, moving quickly, being sneaky, and spending a significant amount of time detached from their main armies.