Common phases of software development models

Exit Criteria and Sign-Offs

Milestone mechanisms used at the end of SDLC phases to stop errors from cascading downstream into subsequent phases.

Evolutionary Iteration (Agile/Scrum)

A development approach that compresses the entire lifecycle into repeating 2 to 4 week sprints.

Verification Iteration (V-Model)

A model that explicitly maps each execution phase directly to a corresponding validation phase.

Risk-Driven Iteration (Spiral Model)

A lifecycle model designed for complex, high-risk projects that spirals outward through four quadrants repeated over multiple cycles.

Shift Left Testing

The practice of introducing testing and quality assurance concepts earlier into the software development lifecycle.

Software Requirements Specification (SRS)

The master planning document containing all user requirements, business rules, constraints, and scope boundaries.

System Architecture Design

The high-level design phase activity of selecting the tech stack, establishing architectural patterns, and defining integration strategies.

Entity-Relationship Diagram (ERD)

A low-level design diagram that logically organizes database entities, attributes, and relationships before coding.

Continuous Integration (CI)

An automated system configured during construction to build and compile code automatically whenever a developer submits updates.

User Acceptance Testing (UAT)

The phase where end-users or client stakeholders test the software in realistic scenarios to grant final launch approval.

Big Bang Deployment (Direct Cutover)

A release strategy where the old system is immediately replaced by the new system all at once, carrying high risk but lower initial cost.

Parallel Implementation

A rollout strategy where old and new systems run simultaneously for a period to minimize risk at the expense of higher resource usage.

Phased Implementation

An implementation strategy where new software is introduced incrementally by module, department, or physical location.

Hypercare Support

Intensive, dedicated support provided immediately following go-live to handle user issues, panic, and critical launch bugs.

Corrective Maintenance

Maintenance performed to fix bugs and issue emergency hotfixes for active issues in production.

Adaptive Maintenance

Maintenance focused on updating software to remain compatible with evolving hardware, operating systems, external APIs, or laws.

Perfective Maintenance

Maintenance focused on enhancing application performance, optimizing database queries, and refining UI features based on user feedback.

Preventive Maintenance

Proactive maintenance actions—such as code refactoring, security patching, and server health audits—designed to prevent future failures.