Number of Tiers (N-tier)
Definition - What does Number of Tiers (N-tier) mean?
In n-tier, "n" refers to the number of tiers being used, such as 2-tier, 4-tier, etc. By breaking an application into tiers, developers can modify or add layers without having to rewrite the entire application. Application architectures exist in the seventh layer of the OSI model.
A number of tiers architecture may also be refereed to as multi-tier.
Techopedia explains Number of Tiers (N-tier)
Generally, the computing architecture based on n-tier concepts are independent of each other. In other words, each tier - and its respective logical layer - can be modified, updated and executed separately. N-tier architecture is based on concepts from distributed computing and client/server computing architecture.