A horizontal structure in a business means the company has little to no middle management and top managers interact directly with customers. This type of flat structure is fairly common in small companies.
Top managers also have more close interaction with front line employees on a daily business in a horizontal structure compared to a vertical structure. One of the main reasons a small business starts with a horizontal structure is because it has a limited employee count. Because of the lack of mid-level managers, horizontal structures are typically less expensive to operate. Employee morale is also normally higher because of the close interaction with top management.