In one tier application the UI/Server(business
logic)/Database resides on one node.

The most basic type of client-server architecture employs
only two types of nodes: clients and servers. This type of
architecture is sometimes referred to as two-tier.

The 3-Tier architecture has the following three tiers.

   1. Presentation Tier
   2. Logic Tier / Business Logic Tier / Transaction Tier
   3. Data Tier

Where N-Tier Architecture contains each modules resides in
different node, which are as follows
1. Presentation GUI.
	(HTML, Windows Forms etc.)
2. Presentation Logic Tier.
	- The Web(VB Script,VB.Net,Java Script etc.)
	- Proxy Tier(SOAP,COM,DCOM etc.)
	- Client interface
3. Business Tier.
	(Business Objects and Rules)
4. Data Access Tier.
	(Interfaces that handles all the Data I/O)
5. Data Tier.
	(Storage,Query)