A digital video recorder (DVR) is an advanced version of a VCR that records and plays back video digitally to a hard drive rather than using tapes. There are two main types: standalone DVRs, which do not require connection to other devices, and PC-based DVRs, which can expand camera support by adding cards to a computer. DVRs offer benefits like monitoring multiple cameras simultaneously, easy sharing and storage of compressed video on portable media, and better security than analog tape systems.