Metal nanoparticles are very attractive because of their size- and shape-dependent properties. From the plethora of existing procedures for the synthesis of metal nanoparticles, this chapter discusses the most widely used wet-chemical methods, which are suitable for the production of both spherical and anisometric (rod-like or prismatic) nanoparticles. It describes the basics of the origin of optical properties of the nanoparticles and presents some of the theoretical methods accounting for them. The chapter also discusses some of the most widely used methods based on chemical reactions in solution (often termed ‘wet chemistry’) that yield metal nanoparticle colloids. The optical properties of small metal nanoparticles are dominated by the collective oscillation of conduction electrons resulting from the interaction with electromagnetic radiation. These properties are mainly observed in gold, silver, and copper, because of the presence of free conduction electrons.