Why does the Asp.net three-tier architecture use the n-tier architecture?

Why does the Asp.net three-tier architecture use the n-tier architecture? Because each layer can only change a small amountCodeIt can be used on different servers physically, because the layer does not know any other layer of the application.ProgramThere are usually three layers: The presentation layer, the business layer, and the data layer. The presentation layer is used to display user interfaces, and the class and object at the business layer are used to drive these interfaces in Asp.net, this layer includes the ASPX page, user control, server control, and some security-related classes and objects. The business tier (BLL) business layer is used to access the data layer, retrieve, modify, and delete data from the data layer, and return the results to the presentation layer. In Asp.net, this layer uses sqlclient to retrieve, update, and delete data from the database, and return the obtained data to the presentation layer. The returned data may only have one Integer type. The data tier (DLL) data layer is a database or data source. In. net, it is usually an SQL Server which is not only a database but also XML