Metamaterials and metasurfaces have attracted much attention due to their powerful ability to control electromagnetic (EM) waves. In this paper, we review the recent developments in the field of EM metamaterials, starting from their exotic physics to their applications in novel information systems. First, we show the fundamental understanding on traditional metamaterials based on the effective medium theory and related applications, such as invisibility cloaks and meta-lenses. Second, we review the two-dimensional versions of metamaterials, i.e., metasurfaces, for controlling spatial waves and surface waves and thereafter present their typical designs. In particular, we briefly introduce spoof surface plasmon polaritons and their applications in mi-crowave frequencies. Following the above approach, we emphatically present the concepts of digital coding metamaterials, pro-grammable metamaterials, and information metamaterials. By extending the principles of information science to metamaterial designs, several functional devices and information systems are presented, which enable digital and EM-wave manipulations simultaneously. Finally, we give a brief summary of the development prospects for microwave metamaterials.