Layered Architecture, also known as n-tier architecture, is a design pattern in software engineering that organizes a system into distinct horizontal layers, each responsible for a specific aspect of the application. This approach enhances modularity, simplifies development, and promotes a clear separation of concerns, making the application more maintainable and scalable.

The architecture typically consists of four main layers. The Presentation Layer is the topmost layer and is responsible for handling user interfaces and interactions. It communicates with the user and sends input data to the lower layers. The Application Layer (or service layer) manages application-specific logic, such as controlling workflows and processing commands. Below it is the Business Layer, which contains the core business logic, rules, and policies of the system—this layer is central to fulfilling the system’s objectives. Finally, the Data Access Layer is responsible for interacting with the data source, such as a database or an external API, to store, retrieve, and manipulate data.

Layered architecture brings several benefits. It improves modularity, allowing developers to work on different layers independently. It enhances testability and reusability, since each layer can be tested and reused in isolation. It also supports scalability and maintenance, as updates or modifications can be made to a single layer without affecting the others.

However, there are some trade-offs. The multiple layers can introduce performance overhead due to additional inter-layer communication. If not implemented correctly, layers may become tightly coupled, which can reduce flexibility and hinder future development. Over-complication with too many layers can also lead to unnecessary complexity.