STLC will come under SDLC.
SDLC means Software Development Life Cycle

It has the following phases....
1) Requirement Analysis
2)System Study Analysis
3) Design
     3.1) High Level Design(HLD)
     3.2) Low Level Design(LLD)
4)Coding
5)Testing
6) Implementation
7)Maintenance 


In STLC (System Testing Life Cycle)

1) System Study
2)Test Plan
3)Test Cases
4) Execute the Test cases
5)Requirement Traceability Matrix
6)Test Execution Report
7)Project Closure Meeting