This chapter is an in-depth examination of noble metal nanoparticles, specifically gold (Au), silver (Ag), copper (Cu), platinum (Pt) and palladium (Pd) about their physical, chemical, optical, electrical and magnetic properties. These particles have special features that enhance their reactivity and interaction with the environment due to their nano-level sizes. In chemistry, Ag and Cu should be made passive to avoid oxidation while Au and Pt are known for their stability as well as resistance to oxides. These principles have essential implications like photothermal therapy and sensing. These nanoparticles possess an elevated electrical conductivity, thus suitable for electronics. Despite lacking intrinsic magnetism, interactions with other materials enhance their magnetic properties, particularly towards Pt. This extensive study illustrates how noble metal nanoparticles can be manipulated and harnessed technologically. Surface plasmon resonance (SPR) is shown optically by these nanoparticles; in particular, Au and Ag exhibit substantial SPR in the visible region, which results in notable light scattering and photothermal effects. The real (ε′) and imaginary (ε″) components of permittivity are explored in this chapter. ε′ is related to light storage and scattering, while ε″ is related to light absorption and heat dissipation.