The concept is similar to Hidden Pair but even more challenging to identify. As seen in the case of Naked Triple vs. Naked Pair, in most scenarios, not all values will be present in all cells.
In the example below, values 2, 4, and 8 form a hidden triple in the last column. Despite the absence of 4 in the uppermost cell and 2 in the bottom cell, these three numbers are exclusively found in the three dark-shaded cells. As a result, all other values can be eliminated from the dark-shaded cells.
See it in a real Sudoku
Open this moveHard #35 in the 1200 Sudoku Medium to Hard book, move 13. Open the app at this move and step through it.