two-tier architecture

[gk]

In three-tier architecture we know we have 3 tiers , presentation
layer ,business(logic) layer, database(data) layer.

In two-tier architecture , what are the two layers ? which layer will
be missed here ? or we can count any two layer from the above ?

 

[Hole]

In three-tier architecture  we know we have 3 tiers , presentation
layer ,business(logic) layer, database(data) layer.

In two-tier architecture , what are the two layers ? which layer will
be missed here ? or we can count any two layer from the above ?

In the two-tier architecture, presentation and business logic are in
the same tier.
(That doesn't mean that the two are strongly coupled...look for the
difference between tier and layer definitions).