Flat architecture is a design approach in software and system development where components or modules are organized at the same hierarchical level, minimizing or eliminating deep layers of abstraction. This structure promotes simplicity, direct communication between components, and easier navigation, as there are fewer dependencies and less complexity compared to multi-layered or hierarchical architectures. Flat architecture is often favored for smaller projects or systems that require rapid development and straightforward maintenance, but may become challenging to manage as the system grows in size and complexity.