Techniques · Not Easy
Claiming
Claiming runs pointing in reverse. Take a digit in a row. If every cell that can still hold it sits inside a single box, the row has claimed that digit for the box. The rest of the box loses it. A column can claim a box the same way.
The usual name in print is box-line reduction. On this site it shares a grade with pointing, because a player meets them at the same moment: the singles have run out, and a digit is locked to the overlap of a line and a box.
When it shows up
Claiming is the other half of the Not Easy grade. A Not Easy puzzle's hardest step is pointing or claiming, never a pair.
NYT Medium always needs pointing or claiming. The archive doesn't separate the two; both are the locked-candidate step that Medium never skips.
See it on a real puzzle
The marks are the candidates left when this is the next step in the solve. Step through it: the pattern, what leaves, and what that forces.
See the pattern
Look at the 3s in this row.