## TL;DR

HashiCorp Consul (2014) is a service mesh and service discovery tool. It provides: service registration + health checking, key-value store, secure service-to-service communication (mTLS + authorization), and multi-datacenter support. Service mesh: sidecar proxy (Envoy) routes and secures traffic.

## Core Explanation

Service discovery: DNS or HTTP API — `my-service.service.consul`. Health checks: HTTP, TCP, script, TTL. KV store: consistent (raft), used for feature flags, dynamic config. Connect: service mesh with intentions (access control policies). Consul KV integrates with Vault for secret storage. Multi-datacenter: WAN federation via gossip protocol.

## Further Reading

- [Consul Documentation](https://developer.hashicorp.com/consul/docs)