Digital Twin is a new technology that is taking over manufacturing and production processes while lowering their costs. This technology has proven to be a key enabler for efficient verification and validation processes, stressing out the importance of its own validation and accreditation phase. This study will emphasize the importance of validation and verification for these DTs, as well as Models and cyber-Physical Systems. Current V&V techniques will be listed and described in this paper, addressing what Model requirements are necessary to validate and translate them to DT.