What is a Product Requirement Document?
A PRD is a document that specifies what a product or feature should accomplish, who it serves, how success is measured, and the detailed requirements for building it. It bridges the gap between strategy ("we need to improve onboarding") and execution ("here is exactly what the new onboarding flow does").
Modern PRDs are not the 50-page waterfall documents of the past. They are concise, living documents that evolve as the team learns. The best PRDs are 3-5 pages and focus on clarity over completeness.
Why PRDs Matter
Without a PRD, requirements live in the PM's head, scattered Slack messages, and half-remembered meeting conversations. Engineers fill gaps with assumptions. Designers interpret requirements differently than the PM intended. QA does not know what "done" looks like.
A good PRD prevents rework. When requirements are explicit and shared, the team builds the right thing the first time. When requirements are ambiguous, you discover misunderstandings during code review or, worse, after launch.
How to Write a Good PRD
Start with context: the problem, the target user, and why this matters now. This is the product brief section. Engineers who understand the "why" make better implementation decisions.
Define user flows. Walk through the feature from the user's perspective: what do they see, what actions are available, what happens when they click? Include the happy path and key error states.
Write acceptance criteria for every user story. These are testable conditions that define when the story is done. "Users can filter results by date range" is testable. "The filter should be intuitive" is not.
Document edge cases. What happens when the list is empty? What about users with 10,000 items? What if the API times out? Engineers will hit these cases. Better to think through them upfront.
Specify what is out of scope. Explicitly list what you are not building. This prevents scope creep and manages stakeholder expectations.
PRDs in Practice
Stripe's PRDs are famously well-structured. They start with a "context and motivation" section, followed by user-facing behavior, API specifications, and migration plans. The emphasis is on developer experience and backward compatibility.
At Linear, PRDs are lightweight documents stored as Linear issues with linked sub-issues. The format is less formal than a traditional PRD but captures the same essential information: problem, solution, and acceptance criteria.
Common Pitfalls
- Writing a novel. If the PRD is longer than 5 pages, it probably includes implementation details that should be left to engineering.
- No acceptance criteria. Without clear criteria, "done" is subjective and arguments follow.
- Static documents. PRDs should be updated as the team learns. A PRD written 6 weeks ago may no longer reflect current understanding.
- Skipping the "why." Engineers who understand the problem often find better solutions than the one specified. Include the context.
Related Concepts
PRDs build on product briefs and are informed by product discovery. They decompose into user stories with acceptance criteria. The definition of done determines when a PRD's requirements are met. See also PRD for the existing general term.