The Hunter's Guild, a large self-governing organization that runs all of the legal activities of Hunters throughout the different cities and the villages. The Guild runs a wide span of operations from the hiring of hunters to research of creatures and development of new weapons and technology to fight them.
Aside from being a requirement to join for all Hunters, the Guild has strict rules to ensure that there is no overpopulation of creatures while still making sure that none are hunted to the point of endangering a species. They take requests from all manner of people willing to pay for their services, and taking a small portion of the fee for hunters to take the requests. The Guild even have different licensing grades for the hunters to ensure no hunter takes a quest that's too dangerous for them. A player's Guild Card represents the license in Monster Hunter Freedom 2 and Unite
A Guild maintained and funded research airship is visible during most missions in Monster Hunter Freedom 2 and Unite, the function of this seems to be to make sure that Hunters can leave the area safely while monitoring creatures from a safe distance for research on their habits and natural ecology.
The Guild runs Gathering Halls in different villages where access to major cities is limited or completely unavailable.