Look at column 1 of the puzzle. Three cells are highlighted in blue at A1, B1 and C1. Collectively, they contain only three
candidates, namely 1, 6 and 9. Although we can't say at this stage which cell will be solved by each number, at least we can say that none
of the other cells in column 1 can have 1, 6 or 9 as a solution. So, referring to the candidates highlighted by a magenta background,
we can say that F1 cannot have a solution of 1 or 9 and G1 cannot have a solution of 1. These three candidates may therefore be removed.

Naked triples may also appear in rows and boxes.