This handbook is a set of working notes, not a course with a finish line. Start with the question in front of you, then choose the page type that matches the job.
Choose a page type
- Guide: Follow a path to complete a task, such as tracing a request or checking a system's failure modes.
- Explanation: Build a mental model for one idea, such as why a queue changes the shape of a system.
- Reference: Look up a stable fact, field, status code, or term.
If you are still forming the question, read an explanation first. If you know the outcome you need, open a guide.
Read for constraints
Every design choice in a backend has a cost. As you read, ask four questions:
- What does this part make easier?
- What does it make slower, less reliable, or harder to change?
- What must be true for the choice to work?
- What happens when that assumption fails?
Those questions turn a list of technologies into a model you can use.
Keep a small example
When an idea feels abstract, attach it to one request. For example, POST /orders might validate input, write an order, publish an event, and return 201 Created. The details expose the real questions: what can retry, what must be atomic, and what does the client see when the event publish fails?
Continue with a request from browser to database.