Over the past few years, the flexibilities of the metamaterials in choosing the numerical value of the effective permittivity or permeability have led to kinds of novel theoretical and practical possibilities for different applications, ranging from microwave to optical regime. In this paper, we discuss the theoretical basis by which metamaterials can manipulate the electromagnetic waves, and further discuss their applicability to various devices or components, including dual-polarization ultra-thin lenses and. We believe that the results suggest promising applications in the next-generation communication system.