Claiming (Box-Line Reduction)
Level: Basic
When a line's candidates for a number all fall in one box, remove that number from the rest of the box.
Claiming (Box-Line Reduction) works in the opposite direction from Pointing. It applies when, within one row or column, all candidates for a specific number lie inside a single box.
That number must go in one of the cells where this line and box overlap, so you can eliminate it from the rest of the box's cells that lie outside the line.
Together with Pointing, this technique uses the interaction between boxes and lines, and it's frequently needed in intermediate puzzles.