Single Tier—Two Layer Model

In this type of solution, we will still have only one web project, but we will separate the UI code into one namespace, and the BL and DAL into another namespace.

ASP.NET Web Project that has two folders:

Here, as the business logic and data access code are logically separated from the presentation code, we have two layers. However, as all code files would still be compiling into assemblies under a single project's /bin, we will have only one tier. We can use this model for projects that have little or no business logic but need to access a database for content.