Tier Architecture

Dear All,

What is Tier Architecture.............
Single, Two, Three & N Tire...???


I need details about that.....

Go through the following links.....

[URL="http://www.faqs.org/faqs/client-server-faq/section-7.html"]Two-Tier Architecture[/URL]

[URL="http://www.faqs.org/faqs/client-server-faq/section-8.html"]Three-Tier Architecture[/URL]

[URL="http://en.wikipedia.org/wiki/Multitier_architecture"]Multitier Architecture[/URL]