3-Layer Architecture
When I started programming in C# back in 2010 in Prague (Czech Republic), the dominant trend was the 3-layer monolithic architecture. This approach splits an application into a presentation layer, a business layer, and a database layer.
For some reason, however, this concept was often misunderstood. Instead of layers, people treated them as independent components that could talk to each other "whenever it made sense." Senior developers during interviews would strictly insist that the business layer must sit precisely between the presentation and database layers, and that you must never communicate directly from the presentation layer to the database—or, God forbid, vice versa.
The bizarre legacy projects where the UI and the database communicate directly with each other in both directions, while the "business layer" serves merely as a dumping ground for helper code "when things get too complicated," date back to this era.
Onion Architecture
