# Learn

This section holds the long-form deep dives in the NATS documentation. Each deep dive walks through one subsystem from first encounter to working confidence, building up a single running scenario, the Acme `ORDERS` platform, step by step.

Deep dives sit between two other layers of the docs:

* **[Concepts](/concepts/intro.md)** Short primers and Getting Started. Read those first if you're new to NATS.
* **[Reference](/reference/.md)** Exhaustive, versioned catalog of every configuration option, header, and wire-protocol detail. Deep dives link out to Reference for the full surface area, since Reference is a catalog rather than a teaching resource.

Every deep dive follows the same pattern: it uses one running scenario, introduces at most two new concepts per page, provides runnable examples in CLI and the client libraries, and links out to Reference for the remaining detail.

## Develop

Build applications with NATS.

* **[Core NATS](/learn/core-nats/.md)** the foundation: publish-subscribe, subjects and wildcards, request-reply, queue groups, and scatter-gather.
* **[Services](/learn/services/.md)** the micro request-reply framework: endpoints, groups, discovery, observability, and scaling.
* **[JetStream](/learn/jetstream/.md)** the persistence layer: streams, consumers, and the acknowledgment loop, built up from a single `ORDERS` stream.
* **[Resilient Clients](/learn/resilient-clients/.md)** production-grade connections: reconnection, drain, slow consumers, request-reply resilience, and TLS plus auth.
* **[Key-Value Store](/learn/key-value/.md)** buckets, watches, history and revisions, TTLs, and how KV sits on top of a stream.
* **[Object Store](/learn/object-store/.md)** chunked blobs over JetStream, with metadata, links, and listing.

## Operate

Run, scale, and secure NATS.

* **[Topologies](/learn/topologies/.md)** Topological shapes: a single server growing into a cluster, a super-cluster, and leaf nodes at the edge.
* **[Security](/learn/security/.md)** authentication, authorization, and accounts: centralized and decentralized auth, TLS, and auth callout.
* **[Clustering & Replication](/learn/clustering/.md)** the mechanism under a cluster: routes and gossip, RAFT and leaders, `R=3` quorum, placement, and peer management.
* **[Monitoring & Observability](/learn/monitoring/.md)** the monitoring endpoints, JetStream health, advisories and events, and Prometheus with dashboards.
* **[Backup & Recovery](/learn/backup-recovery/.md)** stream snapshots, mirrors for disaster recovery, a recovery runbook, and backing up identity.
* **[Deployment & Upgrades](/learn/deployment/.md)** production: sizing, Kubernetes, config management, rolling upgrades, and hardening.

## Where to start

If you're new to NATS, start with the [Core NATS deep dive](/learn/core-nats/.md); it's the foundation every other chapter builds on. If you're already comfortable with the basics and here for persistence, go straight to the [JetStream deep dive](/learn/jetstream/.md).