System Development Life Cycle Model (SDLC Model):
This is also called as Classic Life Cycle Model (or) Linear
Sequential Model (or) Waterfall Method.

SDLC means (Software Development Life cycle):
as  it consists of 6 phases.
1) Initial 
2) Analysis
3) Designing
4) coding
5) Testing
6) Delivering& Maintanance.

SDLC is project management technique used to divides 
complex projrcts into smaller, easily managed segments or 
phases.

QA methodology:

initiation
Test planing
Design
Development
test execution
implementation
Maintenance

SDLC::: Software development life cycle

we have different stages in SDLC for better project output::

1) Requirement 
2) Design
3) Coding
4) Implementation
5) Testing
6) Deployment