Consul

1. Architecture

   Agents, servers, clients, datacenters and the control/data plane.

2. Service Discovery

   Registering services and discovering them via DNS and HTTP.

3. Services and Health Checks

   Service definitions and health checks.

4. DNS Interface

   DNS queries, service lookups and DNS forwarding.

5. Key/Value Store

   Dynamic configuration through the KV store.

6. Consensus and Gossip

   Raft consensus and gossip protocol.

7. Service Mesh

   Sidecar proxies, intentions and mTLS between services.

8. Configuration Entries

   Central configuration of proxy defaults and routing.

9. Gateways

   Ingress, API and terminating gateways.

10. ACL System

    ACL tokens, policies and roles.

11. Gossip and TLS Encryption

    Gossip encryption and RPC TLS.

12. Multi-datacenter and Cluster Peering

    WAN federation, cluster peering and admin partitions.

13. Consul on Kubernetes

    Deploying Consul in Kubernetes.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.