Software specifications capture the "what" and "why" before implementation addresses the "how." Well-structured requirements documents, architecture decisions, and executable specs reduce ambiguity, a
Documentation & Requirements
Overview
Software specifications capture the "what" and "why" before implementation addresses the "how." Well-structured requirements documents, architecture decisions, and executable specs reduce ambiguity, align stakeholders, and create verifiable acceptance criteria.
Document Types
Requirements Documents
Type
Audience
Focus
PRD (Product Requirements)
Product + Engineering
Features, user stories, success metrics
TRD (Technical Requirements)
Engineering
Architecture, APIs, data models, constraints
BRD (Business Requirements)
Business + Leadership
ROI, market need, business objectives
Architecture Documents
Type
Audience
Focus
ADR (Architecture Decision Record)
Engineering
Single decision with context and consequences
RFC (Request for Comments)
Engineering + Stakeholders
Proposed change seeking feedback
Executable Specifications
Type
Audience
Focus
Gherkin (Given/When/Then)
QA + Product + Engineering
Acceptance criteria as executable tests
Gauge (Markdown specs)
QA + Engineering
Free-form test specifications in Markdown
Document Flow
Business Need
│
▼
BRD ──► "Should we build this?"
│
▼
PRD ──► "What are we building?"
│
├──► ADR ──► "Why did we choose X over Y?"
│
▼
TRD ──► "How do we build it?"
│
├──► RFC ──► "Proposing approach Z for feedback"
│
▼
Gherkin / Gauge ──► "How do we verify it works?"
│
▼
Implementation + Automated Tests
Best Practices
Write the PRD before the TRD — define what you're building before deciding how to build it.
Use ADRs for every significant architecture decision — they're short, structured, and invaluable for future developers.
Make specifications executable where possible — Gherkin and Gauge connect written specs directly to automated tests.
Keep documents close to the code in the same repository so they evolve together.
Use lightweight templates rather than heavyweight processes — a short, focused ADR beats a 50-page design doc nobody reads.
Review specs before implementation, not after — specifications are cheapest to change when they're still text.