  We give a description of the Tripos To Topos construction in terms of four
free constructions. We prove that these compose up to give a free construction
from the category of triposes and logical morphisms to the category of toposes
and logical functors. Then we show that other similar constructions, i.e. the
one given by Frey in \cite{frey} and that of Carboni in \cite{carbons} are
instances of this one.
