Logging Best Practices

Logs are how a running program tells you what it did. Without them, debugging a production bug means guessing, and tracing a customer's failed order across three services becomes archaeology. This chapter covers the modern .NET logging stack: ILogger<T>, log levels, structured logging with placeholders, scopes for correlation, source-generated logging for performance, and what to keep out of your logs entirely. The running example is an e-commerce order-processing flow, and every code sample runs on .NET 8 or later.