Mirrored from Sudopedia, the Free Sudoku Reference Guide
Within the context of Sudoku, a pattern can be:
Players often make a distinction between pattern-based solving techniques and chains or loops. However, recent developments in solving techniques have resulted in several advanced solving techniques where patterns are embedded as nodes in chains.
Note that a single ALS is a pattern, but not a solving technique. The techniques that use ALS either require more than one or use them in chains.