The Software Development Lifecycle (SDLC) is the structured framework guiding software creation from initial concept through ongoing maintenance, encompassing planning, design, development, testing, deployment, and support phases. Modern SDLC integrates quality gates, continuous feedback loops, and automated workflows to deliver reliable software aligned with business objectives. SDLC isn't a single rigid path—it adapts through models like Waterfall, Agile, DevOps, and Spiral, each optimized for different project contexts, risk profiles, and organizational needs. Understanding SDLC phases, deliverables, and governance checkpoints is essential whether building a startup MVP, migrating enterprise systems, or implementing regulatory-compliant applications—the lifecycle provides the blueprint for predictable, maintainable software delivery. As of 2026, AI-assisted development tools and DevSecOps practices are reshaping every phase of the lifecycle.
What This Cheat Sheet Covers
This topic spans 21 focused tables and 178 indexed concepts, 157 flashcards. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
A jump-to index of every table row in this cheat sheet.
An interactive map of every table and concept in this topic.
Table 1: Core SDLC Phases
Every software project flows through these seven phases, though iterative and Agile models revisit earlier phases frequently. Each phase has specific entry criteria, activities, and exit deliverables that act as quality checkpoints before the next phase begins.
| Phase | Example | Description | |
|---|---|---|---|
Project charter creation Stakeholder identification | • Defines project scope, feasibility assessment, resource allocation, timeline estimation, and success criteria • establishes business case and ROI justification. | ||
Functional specifications User stories and acceptance criteria | • Gathers and documents what the system must do • captures business needs, user expectations, constraints, and compliance requirements through stakeholder interviews and elicitation techniques. | ||
Architecture diagrams Database schema design | • Translates requirements into technical blueprints • defines system architecture, data models, interfaces, technology stack, security controls, and integration patterns. | ||
def process_order(order): validate(order) save_to_db(order) | • Actual code writing phase • developers build functionality according to design specs, following coding standards, version control practices, and code review processes. | ||
Unit tests: pytest functions Integration tests: API validation | • Verifies software meets requirements and is defect-free • includes unit, integration, system, UAT, performance, and security testing before production release. | ||
Blue-green deployment Canary releases | • Moves tested code to production environment • includes release planning, environment configuration, data migration, rollback strategies, and go-live coordination. | ||
Bug fixes and patches Feature enhancements | • Ongoing operational phase • handles production issues, applies updates, monitors performance, adapts to environmental changes, and implements user-requested improvements. |