Definition of handlers:
(n) :
(literally) One who handles something (especially manually) or someone.
(n) :
A controller, trainer, someone who handles a specified thing, animal or person (especially a prizefighter).
(n) :
An advisor or manager providing guidance to a person occupying public office or a prominent position.
(n) :
(programming) A subroutine that handles a particular situation such as an event or exception.
(n) :
A surname.