Implies a division of responsibilities in logical components usually, presentation layer, business / domain layer & data Access layer within a single running process.

Benefits

• Core use of this architecture is for sake of Maintenance And reusability
• The use of layers helps to control and encapsulate the complexity of large applications.
• Easy deployment strategy
• Higher performance

Liabilities

• Lower performance under load.
• Dangers of coupling as there are no physical separation of layers
• No scaling of layers possible. Scaling only possible by duplication entire application process.
• Unable to perform maintenance on layers without affecting the application as whole.
• Unable to unit test and performance test each layer independently from the rest of the application.