Horizontal

The horizontal approach looks at the system as a layered architecture. The team structure is organized along those layers. There may be a frontend group, backend group, and a DevOps group. Each group is responsible for all the aspects in their layer. Vertical functionality is implemented by a collaboration between different groups across all layers. This approach is more suitable for smaller organizations with a small numbers of products (sometimes just one).

The nice thing about the horizontal approach is that the organization can build expertise and share knowledge across entire horizontal layers. Typically, organizations start with a horizontal organization and, as they grow and then expand to more products, or possibly spread across multiple geographic locations, they divide into a more vertical structure. Within each silo, the structure is usually horizontal.