What does "in the trade" mean in gay culture?

expression used by those in the business of selling their bodies for sexual pleasures of others. Prostitution, in other words.

Definition

Known as the 'oldest profession'. Prostitution was openly practised in Ancient Greek society, and earlier. Unlike today, evidence suggests that Prostitution was an accepted part of ancient civilizations.

It also suggests that practitioners of this trade include both sexes, and it should be noted, that these 'professionals' catered mainly to the male population.

This includes a hierarchy, where the more sophisticated were found in special sex houses, others working the streets.