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Wikipedia redirects to a page on "Mulitier Architecture", which says: 

In software engineering, multi-tier architecture (often referred to as n-tier 
architecture) is a client–server architecture in which presentation, application 
processing, and data management functions are logically separated.

Is this like using mySQL to create and query your database, php to allow for interaction, and HTML for presentation?

Thanks!

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    Possible duplicate of http://stackoverflow.com/questions/312187/what-is-n-tier-architecture . Although "distributed systems" are also discussed in a more generalized way (e.g. http://queue.acm.org/detail.cfm?id=2482856) and can indicate separating responsibilities/concerns into discrete service boundaries. – Matt Self Jun 15 '13 at 14:08

1 Answers1

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Pretty much, yes.

A Tier refers to a physical part of the architecture, where as a Layer is logical.

For example, you might have a web-based PHP app that had some presentation (UI) code, some business logic (BL) and some data-access (DA) code all implemented as PHP, running on a web server. Assuming you had cleanly and intentionally kept the UI, BL and DA code seperate then we would say these are logical layers.

But these aren't the Tiers. The three tiers would be the PC running presenting the HTML mark-up (assuming that's what the UI layer spat out), the web-server that handled the request, and the database server where the data was stored (assuming it was seperate, which in most "professional / enterprise" environments it will be.

Adrian K
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