The document discusses different types of application architectures: 1) 1-tier applications have a single layer and run standalone on a desktop, storing data locally. Examples include Notepad and Acrobat Reader. 2) 2-tier or client-server applications have two layers - a client and server. The client sends requests to the server, which responds by fetching data. Examples pair specific clients like VB with servers like SQL Server. 3) 3-tier or multi-tier applications have three layers - a client, application server, and database. The client makes requests to the application server, which communicates with the database to fulfill requests and return data to the client. Examples include common web applications running on