Great explanation Deb.
But I think new comers need to be a little careful while using the Uniqueness rule, it could backfire in many puzzles if used incorrectly.

I have seen people using Unique Rectangles in a Diagonal Sudoku with one of the corners of the rectangle lying on the diagonal.
Also seen puzzle creators using uniqueness while creating a puzzle, before proving that the puzzle has a unique solution.

Amit, agreed, players have to be careful while applying Uniqueness, though it provides shortcuts in many puzzles.
Also, this is not the only logical way to solve the puzzle. But i feel this is the quickest.
If other players have applied some other techniques, request them to post it here.

Thanks Deb for this great explanation. I have applied the uniqueness funda to solve this puzzle during test, but this even odd funda for new to me. Thanks again for putting this method.