Software Development Life Cycle (SDLC) vs. STLC

SDLC (Software Development Life Cycle)

SDLC describes phases to build software:

1. requirements
2. design
3. implementation
4. testing
5. deployment
6. maintenance

STLC (Software Testing Life Cycle)

STLC describes phases to plan and execute testing:

1. requirement analysis (testable acceptance criteria)
2. test planning (scope, tools, risk)
3. test case design
4. test environment setup
5. test execution
6. test closure (reports, lessons learned)

Diagram: SDLC vs STLC alignment

diagram Diagram mermaid

  graph TD
subgraph SDLC
S1[Requirements] --> S2[Design]
S2 --> S3[Implementation]
S3 --> S4[Testing]
S4 --> S5[Deployment]
S5 --> S6[Maintenance]
end

subgraph STLC
T1[Requirement Analysis] --> T2[Test Planning]
T2 --> T3[Test Case Design]
T3 --> T4[Test Environment Setup]
T4 --> T5[Test Execution]
T5 --> T6[Test Closure]
end

S1 --- T1
S2 --- T3
S3 --- T4
S4 --- T5

Key takeaway

SDLC builds the product.

STLC ensures the product is verified systematically.