# Requirements Documentation
This guide covers requirements documentation practices, including Product Requirements Documents (PRDs) and related requirements gathering standards.
## Product Requirements Document
The Product Requirements Document (PRD) serves as the authoritative source for what a product should do, who it serves, and how success will be measured. It bridges business objectives with technical implementation.
### Purpose and Benefits
- **Alignment**: Ensure all stakeholders understand product goals and scope.
- **Prioritization**: Provide clear criteria for making trade-off decisions.
- **Acceptance criteria**: Define measurable success conditions.
- **Communication**: Facilitate discussion between business and technical teams.
- **Change management**: Track requirement evolution throughout development.
### PRD Structure
Use the following structure for product requirements documents:
``` rst
*******************************************************************************
Product Requirements Document
*******************************************************************************
Executive Summary
===============================================================================
[Brief overview of the product, its purpose, and key benefits. Should be
understandable by any stakeholder.]
Problem Statement
===============================================================================
[Clear description of the problem this product solves. Include:
- Who experiences the problem
- When and where it occurs
- Impact and consequences of the problem
- Current workarounds or solutions and their limitations]
Goals and Objectives
===============================================================================
[Specific, measurable goals the product should achieve. Include:
- Primary objectives (must-have outcomes)
- Secondary objectives (nice-to-have outcomes)
- Success metrics and how they will be measured]
Target Users
===============================================================================
[Description of intended users including:
- User personas or roles
- User needs and motivations
- Technical proficiency levels
- Usage contexts and environments]
Functional Requirements
===============================================================================
[Detailed description of what the product must do. Organize by feature area
or user workflow. For each requirement include:
- Requirement ID (for traceability)
- Priority (Critical/High/Medium/Low)
- User story format when appropriate
- Acceptance criteria]
Non-Functional Requirements
===============================================================================
[Technical and quality requirements including:
- Performance requirements (response time, throughput, etc.)
- Scalability requirements
- Security requirements
- Reliability and availability requirements
- Usability requirements
- Compatibility requirements]
Constraints and Assumptions
===============================================================================
[Known limitations and assumptions including:
- Technical constraints (platforms, technologies, etc.)
- Regulatory or compliance constraints
- Dependencies on other systems or teams
- Assumptions about user behavior or technical environment]
Out of Scope
===============================================================================
[Explicitly state what will NOT be included to prevent scope creep and
manage expectations.]
```
### Best Practices
**Requirement Quality**
- **Specific**: Requirements should be unambiguous and precise.
- **Measurable**: Include quantifiable acceptance criteria where possible.
- **Achievable**: Ensure requirements are technically and practically feasible.
- **Relevant**: Each requirement should trace back to business objectives.
- **Testable**: Requirements should be verifiable through testing or inspection.
**User Story Format**
When appropriate, express functional requirements as user stories:
``` text
As a [user role], I want [functionality] so that [business value].
Acceptance Criteria:
- [Specific condition that must be met]
- [Another condition that must be met]
- [Edge case or error condition handling]
```
**Prioritization Guidelines**
- **Critical**: Product cannot launch without this feature.
- **High**: Important for product success but could be delayed if necessary.
- **Medium**: Valuable enhancement that improves user experience.
- **Low**: Nice-to-have feature that can be considered for future releases.
**Traceability**
- Assign unique identifiers to requirements (REQ-001, REQ-002, etc.).
- Maintain traceability from business objectives through requirements to test cases.
- Update requirement status as development progresses.
## Requirements Management
### Change Control
- **Document changes**: Track all requirement changes with rationale.
- **Impact assessment**: Evaluate effects on schedule, resources, and other requirements.
- **Stakeholder approval**: Ensure appropriate sign-off for requirement changes.
- **Communication**: Notify affected teams of requirement updates.
### Review and Validation
- **Technical feasibility**: Validate requirements with development teams.
- **User validation**: Test requirements with actual users when possible.
- **Consistency checking**: Ensure requirements don't conflict with each other.
## Integration with Development
- **Architecture alignment**: Ensure requirements inform architectural decisions.
- **Sprint planning**: Break requirements into implementable user stories.
- **Acceptance testing**: Use requirements as the basis for acceptance test criteria.
- **Progress tracking**: Monitor development progress against requirements completion.