  From this vast subject, I will pick out and review three specific topics,
namely the formation and evolution of bars, the formation of bulges, and the
evolution during multiple major mergers. Bars form naturally in galactic discs.
Their evolution is driven by the exchange of angular momentum within the
galaxy. This is emitted mainly by near-resonant material in the inner disc
(bar), and is absorbed by near-resonant material in the outer disc and in the
halo. As a result of this, the bar becomes stronger and rotates slower. Bulges
are not a homogeneous class of objects. Based on their formation history, one
can distinguish three types. Classical bulges are mainly formed before the
actual disc component, from collapses or mergers and the corresponding
dissipative processes. Boxy/peanut bulges are parts of bars seen edge-on.
Finally, disc-like bulges are formed by the inflow of material to the center
due to bar torques. Major mergers bring strong and fast evolution and can turn
discs into ellipticals. I present results from simulations of multiple mergers
in groups of disc or of elliptical galaxies and discuss the orbital anisotropy
in the merger remnant.
