  I review the main steps made so far towards the construction of a (semi)
analytical model for describing the growth history of bound virialized objects
or haloes in the gravitational instability scenario. I mainly focus on those
models relying on the spherical collapse approximation which have led to the
most complete description. I insist on the different assumptions of each model
and outline their main advantages and shortcomings. The work is divided in two
parts: a first one dealing with the theoretical mass function of objects, and a
second one dealing with the typical growth times and rates. Particular
attention is paid to a new model making the practical distinction between
accretion and merger events.
