Architecture

Single-Tier Architecture:
All components (user interface, business logic, and data storage) run in a single system or application. There is no separation between layers.
Example: A desktop application like Microsoft Access where the user interface, processing, and database are within one system.

Two-Tier Architecture:
The application is divided into two layers:

1. Client Tier (Presentation Layer) – user interface and basic validation.
2. Server Tier (Data Layer) – database server handling data storage and queries.
   Example: A client application (like a desktop app) directly communicating with a database (such as MySQL).

Three-Tier Architecture:
The application is divided into three layers:

1. Presentation Tier – user interface.
2. Business Logic Tier – processes data and applies rules.
3. Data Tier – manages data storage and retrieval.
   Example: A web application with a front-end (HTML/JS), back-end server (Java EE), and a database (MySQL).

Multi-Tier Architecture:
Extends the three-tier model by adding more specialised layers, such as:

• Security Layer
• Caching Layer
• API Layer
• Integration Layer
  This improves scalability, flexibility, and maintenance in large systems.