AFK, meaning "Away From Keyboard", is a status one can have in a chat situation, such as within TLBB. In games this can extend to the status of a character, as no one is controlling it. Within TLBB characters can perform actions whilst the player typically controlling it is AFK, and are particularly designed for this type of game play, when the player cannot give the game direct attention, but wish to advance somehow.
Peddling is recommended to be done whilst AFK.
Being logged in whilst AFK brings the benefit that your energy and vigor are being replenished.