What are Architecture Decision Records (ADRs) and how do you use them?

ADRs document significant architectural decisions with context and consequences. Format: Title, Status, Context, Decision, Consequences. Store in repo (docs/architecture/decisions). Benefits: capture rationale, onboard new members, prevent re-debates, track evolution. When to write: technology choices, design patterns, trade-offs, team conventions. Keep: concise, linked to code/PRs, reviewed. Tools: adr-tools (templating), lightweight text files. Anti-patterns: documenting everything, not updating status. ADRs create organizational memory for why decisions were made.