The subject of the spontaneous formation of patterns in systems far from equilibrium is an exciting and fast-growing branch of
applied mathematics and physics, with strong impact on fields as diverse as ecology, chemistry, and new technologies and processes.
Dissipative systems, in which energy must be supplied through a gradient such in temperature, velocity, concentration,
etc, to maintain the physical instability, are a good step towards a description of this variety of phenomena.
In this talk, the basic mathematical tools in analyzing the selection mechanisms and the dynamics of patterns
in extended dissipative systems are summarized and exemplified on a paradigm system, the electroconvection in nematic liquid crystals.