Embodiments of the present invention generally relate to furniture, housing and office accessories, and interior design. More specifically, embodiments of the invention relate to modular furniture, modular structures, a modular furniture system, and a modular unit for use in the modular furniture, the modular structures, the modular furniture system, and an interior design system. In some embodiments, the modular furniture system comprises a plurality of modular units that can be interconnected to one another to form furniture and other structures. Each modular unit comprises a plurality of side members interconnected to one another using connectors. The connectors can also be used to interconnect one modular unit to another modular unit.