Essential Crates

Why a handful of crates - serde, tokio, anyhow/thiserror, tracing, clap, rayon - became de facto standard-library extensions instead of being folded into std.

The serialization foundation (cross-link).

The async runtime (cross-link).

Application and library error handling.

Structured, async-aware diagnostics.

Command-line argument parsing.

Data parallelism made easy.

HTTP and database access (cross-links).

Dates, times, and durations.

Iterator extensions and randomness.

Lazy statics and concurrent maps.

Choosing well-maintained, aging-well dependencies.