Multitier and multilayer architecture

Tiers and layers are often very similar to each other in names. That can be confusing, but they describe different things.

Tiers are about how you divide your application into different physical representations, you can have one or multi-tier application with multiple layers:

• Presentation tier can be only user device, think about application which only displays data from some API on mobile or printer which prints data.
• Application tier can be a server which computes your data and for that it can communicate with data tier.
• Data tier is a physical database server or storage service (cloud storage) on more servers to read/write data for your application server.

Layers are about how you divide the functionality of code.

• Presentation layer is responsible for presenting data.
• Data layer is responsible for data storing and reading.
• Business layer is responsible for communication between layers and computing.

Many modern frameworks and apps are using layered design, because it's much easier to maintain or grow systems in this type of architecture.