A review of the present status of the problem of metal deposition and electrochemical phase formation and growth is made. The historical background of the problem is given with an overview of the major contributions of different electrochemical schools. Phase formation is treated in classical and atomistic terms. Some of the basic consequences of the theory concerning the equilibrium form, the influence of the substrate, the size-overpotential dependence of low-dimensional systems, and the nucleation kinetics are discussed. The basic modes of crystal growth under electrochemical conditions are described. The influence of substrate surface modification in the UPD region concerning the formation of low dimensional phases and their stability ranges are discussed. The development of recent in situ techniques for nanostructuring and nanomodification of solid surfaces and their importance for electrochemical nanotechnologies are also shortly presented.