.Net design patterns

Before starting a new web application, deciding which design pattern and architecture is totally depends on on the web application and the team size. If we are creating a big web application that means we need take care of a scalability, I am fan of CSLA. Within the application we can introduce the different patterns to solve/implement the different functionality. But I think for a simpler web application having some simple and common functionality MVC pattern is a good choice.

Design Pattern- Patterns are nothing but a set of already established rule that are aleady validated and varified.
Tiers and patterns are basically two diffrent things.
Tiers- Tiers are basically physically saperated layers.eg
MVC- If all the three layesr are at the same location or a single assembly it will be treated as 3 layered and 2 tiered application.
So tier is a subset of layer.
Pattens- Depending on the type of requirement, we can chose already existing patterns so that we can make sure that this is the best way of implemening that problem statement.
Eg Suppose we are sending mailsfrom our application so there will be a single Mail server- Best design pattern to choose Singeton
For any more clarification feel free to contact 

Basic need of design pattern arise when we want to make the application scalable and loosely coupled.Basically design pattern we implement either in business logic layer or Data Access Layer Component so that we can easily separate all the component and can put on different physical n tier so that later on we can scale out although there will be network latency due to interprocess communication but we can avoid tight coupling and scale out the application.

Architecture will depend upon the type of project, availability of team members, communication between different participants and various.
Similarly design pattern will depend on your need, and be aware don't fit design patterns every where just use them when needed.

I think no one can stick with 3 tier or MVC in big or mid-size project. You will factory pattern and n-tier in your project. And I you are working with ASP.NET then you automatically working in MVC pattern too. Yeah MVP is slightly different when you use MVP Blocks published by Microsoft. There are number of pattern now a days Microsoft launch. And Believe; you do not need to learn all pattern. The important thing is this how much you aware Object Oriented Programming.

Design Patterns are ideally suited to developing .NET applications because the .NET platform is fully object oriented. In .NET, everything is an object. The type of design pattern depends. It can be 3-tier, n-tier, or MVC... Think before using 

Design patterns are there to assist you to help you in solving the problems - if you are new to DP , please refer to my blog link http://sujayghosh.wordpress.com/2008/05/29/why-should-you-use-design-patterns/ .

Dont use things just because you have to , please think whether you really need to use it. If the code is well structured, loosely coupled , then probably you dont need a design pattern at all. 

Hope this helps.

A lot of design patterns are available for web application as few mentioned by Parth.But I aggree with Darpan that the final decision is made on need like what kind of web application you want to create
for e.g. Normal web application or Rich Internet Applications.
So if you are specific with your requirement then might be we can help you.

Of course Darpan,

I even agree with you. I just mentioned name of different architectures for the reference of people. I prefer to use 3-tier classic architecture if the scope of the project is not wider. I only go for N-tier if there is no other choice. Btw, I am not fan of MVC.

Parth ... I will say that it all depends on the need ortherwise it can be an overkill

Let me just clear the question first comes in anyone's mind. Are you talking about 3 tier, N-tier or MVC architecture?

Is ita a question???