  The formal theory of breakup reactions is reviewed. The direct breakup
mechanism which is formulated within the framework of the post form distorted
wave Born approximation is discussed in detail. In this theory, which requires
the information about only the ground state wave function of the projectile,
the fragment-target interactions are included to all orders while
fragment-fragment interaction is treated only in the first order. The general
applicability of this theory to describe the breakup of halo nuclei is
demonstrated by comparing the calculations with data for total, as well as
energy and angle integrated cross sections and momentum distributions of
fragments in reactions induced by a number of halo nuclei. We investigate the
role played by the pure Coulomb, pure nuclear and the Coulomb-nuclear
interference terms. Postacceleration effects in the Coulomb breakup of neutron
halo nuclei is also studied.
