This talk will report on the development and the exploitation of gyrokinetic codes carried out at DRFC-Cadarache in collaboration with various laboratories. These codes solve a low frequency limit of the Vlasov equation for magnetized plasmas, obtained by time averaging over the ion cyclotron period. This approximation replaces the motion in the six-dimensional phase space of charged particles in an electromagnetic medium, by the motion in a lower dimensional space parameterized by one (or more) conserved quantities. The equation is then coupled to the Maxwell equations for the evolving fields. Further approximations that depend on the physical problem may also be employed. The main effort is currently on the development of a 4D+1P (four dimensions + one parameter, the magnetic moment) electrostatic code (i.e., the magnetic field is given and static) in cylindrical geometry. Accurate integration and excellent energy conservation was achieved by employing a semi-Lagrangian integration scheme, which exploits the constancy of the distribution function on the characteristics of the kinetic equation. First results on the formation of convective cells driven by the ion temperature gradient will be presented. A second class of codes, where the distribution function depends on two-dimensional phase space variables and one or two parameters, were also developed. Results from these codes, showing, in particular, the competition between the formation of convective cells and that of sheared zonal flows (flows perpendicular to the mean gradients), and their effect on convective heat transfer in steady state temperature gradient driven turbulence, will be reported. A third code that aims at simulating magnetic reconnection is also being implemented. This code treats kinetically the electron dynamics in a cold ion fluid. The goal is to understand the evolution of certain internal disruptions, abrupt changes of the magnetic configuration in the interior of the magnetic confinement devices, and to characterize the phenomenon of particle acceleration during these events.