r_nassabeh
3-Layered implies a division of responsibilities in logical components whereas in 3-Tier we privilege a physical division of activities. Take a look at http://blogs.msdn.com/diegumzone/archive/2006/10/09/3_2D00_Tier_2C00_-3_2D00_Layer_2C00_-MVC_3A00_-a-Trio-of-Famous-Trios.aspx
OK, Reza, I do not argue - let's keep this your reference as standard definition for this ASP.NET community?...
I just wanted to note that will we keep it like that or not developers will anyway confuse/mix-up these words because AFAIS there is no clear difference between their meanings in English (I'm not a native English speaker so I might not feel this difference, which is clear for native English language speakers)
Have a look :)
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http://www.m-w.com/dictionary/tier
1 a: a row, rank, or layer of articles; especially : one of two or more rows, levels, or ranks arranged one above another
b: a group of political or geographic divisions that form a row across the map <the southern tier of states>
http://www.m-w.com/dictionary/layer
1: one that lays (as a worker who lays brick or a hen that lays eggs)
2 a: one thickness, course, or fold laid or lying over or under another
b: stratum
c: horizon 2
3 a: a branch or shoot of a plant that roots while still attached to the parent plant b: a plant developed by layering
>>
Thanks.
P.S. From now on I will use "3-tiered" when talking on physical separation of compoenents, and "3-layered" - when talking about logical separation of components (responsibilities)....