Mirrored from Sudopedia, the Free Sudoku Reference Guide
SSTS means Simple Sudoku Technique Set, the set of solving techniques implemented in the Simple Sudoku program.
Because this set has not changed since 2005, it is often used as a benchmark. Some solvers use SSTS in their solving path description to identify the "easy" parts not worth mentioning between the advanced steps.
The set contains the following techniques -- listed by SS hierarchy: