This is our starting grid, so the first thing we always do is look for starting points.
Have a look at the bottom row, in the bottomright corner there is a set of three squares with a '2' in them. The only way we can arrange our black and white squares here is to have the middle square white, and the other two black.
Also, have a look in the second column. Here we have two squares next to each other that have a '3' in them, and an isolated '3' at the top. We don't know which one, but one of the adjacent '3' squares must be white, which must mean that the isolated '3' must be black.

Now that we have a starting point, we know that all black squares must be surrounded by white squares. So, we can go ahead and do that.
As we turn each square white, we need to look, are there any other squares in that row/column with the same number?

Have a look in the first column, when we turned the topleft square white, we can see that there is another '4' in this column, so the other '4' in this column must be black.
Similarly, in the top row, we turned a square with a '2' in it white, but there is another '2' in that row as well, so that one must be black. It's just coincidence that they are next to each other.

We can again turn all those squares around the new black squares to white.

Have a look at the top row, all three white squares in that row are in danger of being isolated from the rest of the white squares in this grid. The only way we can avoid this is by making the square underneath each white square from the top row white as well.

In the middle row, we can turn the '3' black because there is already a '3' in that column. And similarly, we can turn the '5' black because there is also already a '5 in that column.
We then turn all the squares surrounding our black squares to white, and that completes our puzzle!
This Hitori puzzle is actually one of our Daily Hitori puzzles, want to play now?
This is an example 5*5 grid, you can get much bigger grids than this, but generally the bigger the grid, the harder the puzzle is going to be. You're still applying the same set of rules, but it can get very complicated!
