Mirrored from Sudopedia, the Free Sudoku Reference Guide
It has been introduced as a separate technique, because the Turbot Fish technique does not use a single pattern and is not easy to learn by the average Sudoku player.
Here is an example:
The candidates for digit 4 in rows 4 and 7 are conjugate pairs. Since the 2 candidates in column 7 cannot be true together, at least one of r4c2 or r7c1 must be true. They could also both be true. We call this a connected pair. The two red candidates can be eliminated, because they can both see r4c2 and r7c1.