"Locked Candidates" Sudoku solving technique explained:
As you probably came to understand, there are two types of locked candidates techniques. Both techniques work in the form of elimination but each one is a bit different.
Locked Candidates 1
If in a block all candidates of a specific number are bound to a row or column, that number cannot appear outside of that block in that row or column.
Locked Candidates 2
Locked candidate 2 works in the opposite way: If in a row (or column) all candidates of a certain digit are confined to one block, that candidate is eliminated from all other cells in that block.