Metamaterials are artificially constructed of periodic or nonperiodic subwavelength structures, which have trigger broad interests from communities of physical science, microwave engineering, information engineering, etc. Traditional metamaterials are commonly characterized by the effective medium theory. In 2014, the concept of digital coding and programmable metamaterials was proposed, enabling the design of metamaterials from the perspective of digital information. The flexible control of EM waves can be achieved by applying real-time coding sequences onto the digital coding and programmable metamaterials, which simplifies the procedure in designing functional metamaterials. The digital coding and programmable metamaterials combine the physical space with the information space, allowing simultaneous control of the EM physical properties and process of digital information on one single platform. Many applications emerge in new-generation communications, microwave photonics, electromagnetic information theories, etc.