Three-tier architecture overview
The three-tier architecture is the most popular implementation of a multi-tier architecture and consists of a single presentation tier, logic tier, and data tier. The following illustration shows an example of a simple, generic three-tier application.

Architectural pattern for a three-tier application
There are many great online resources where you can learn more about the general three-tier architecture pattern. This whitepaper focuses on a specific implementation pattern for this architecture using Amazon API Gateway and AWS Lambda.