There are two common types of application architecture:
Monoliths have their place. They are easy to get going and often make a lot of sense when you are starting out. However, sometimes your app may grow in size and become difficult to maintain. Then you might want to consider Microservices...
Microservices let you break down your app into little pieces to make them more manageable, replaceable and maintainable. You can also scale out different parts of your app at a granular level.
.NET 6 and Azure have heaps of great tools for developing simple APIs and worker services in a Microservices pattern.
Watch the below video from 35:40 - 46:50
.NET Worker Services make it easier to implement dependency injection, configuration and other syntactic sugar using the same patterns you are familiar with in other types of .NET applications
Azure Functions gives you a great way to build applications in small, modular, scalable and easy to manage chunks. It provides triggers other than http to handle other common microservice patterns
Minimal APIs give you a way to write APIs in just a few short lines of code
Cost - Provides separation of scalability, keep the hot parts of your app hot and the cold parts of your app cold to achieve maximum pricing efficiency
Maintainability - Keep code more manageable by making it bite sized chunks
Simplify code - Write minimal APIs
Deployment - Standardize deployment with containers
Testing - Easier to find problems since they are isolated to a specific part of the app
Cognitive Complexity - Devs can focus on one aspect of the app at a time
Data - You can use the best way of storing data for each service
Language - You can use the best language for each service
Upfront Cost - More upfront work is required
Cognitive Complexity - While individual apps are simpler, the architecture of the app can become more complex
Health Check - It's harder to know if all parts are alive
Domain boundaries - You need to define the separation of concerns between different services. Avoid adding dependencies between services because you can create a domino of failures...a house of cards.
Performance normally suffers as calls are made between services
Without adequate testing it's harder to maintain
Using multiple languages and datastores can be both more expensive to host and require more developers