The two basic types of organization structures are: Vertical and Horizontal Structure. While the Vertical structure is one with many layers of administration, the horizontal system has no or very few hierarchical levels.
Hence, in horizontal organizations the power and decision making capability is decentralized. The people at the lowest levels also have decision making powers in their area of work. But, such a structure becomes difficult to apply in very large organizations. Horizontal organizations are also called flat organizations.
For example: Cisco Systems is a flat organization. Generally start-ups are also flat organizations.