The classic client–server architecture in which presentation, application processing, and data management functions are physically separated.
Source: wikipedia.org
Source: https://aws.amazon.com
N-tier might be good for large projects but doesn't always fit everyday's apps or moderate budgets.
It doesn't mean no more servers but rather focusing on your code as a developer. It's a new way to build apps, FaaS way.
Break your app into micro services, or functions, that are called from your API.
Source: https://aws.amazon.com
Scalable
Affordable
Less setup/maintenance
Embrace component logic
The serverless architecture is great, but deploying it from A to Z might be a tedious task as it involves a lot of web services.
Allows you to deploy auto-scaling, pay-per-execution, event-driven functions to any cloud. Supporting AWS Lambda, Azure functions, Google CloudFunctions, etc.
Source: https://serverless.com/framework/docs/
The serverless framework comes with a CLI tool. You can use it to create, test, push, delete, customize (etc.) your service.
The framework deals with events (e.g. operations on a S3 bucket) and resources (e.g. a DynamoDB stream) to trigger or bind your custom functions.
To describe your environment, simply write a few lines of code in a .yml file. You can define the stage of your service, the region where it runs, the resources and the events it uses, etc.
The second file that is generated by the framework is called handler. It basically lists all the functions of your API and describes your backend logic.
Getting started with serverless architecture and AWS
Serverless Framework documentation