This is an image-slider puzzle. You can pick from 10 different varieties based on the number of rows and columns.
The puzzle is a picture made up of a number of smaller image blocks. There is a small preview picture on the left that shows what the completed puzzle will look like.
Slide the image blocks around until they are in order and you can see the big picture.
The white space is the open space that the image blocks are moved to. To move an image block, click on the block.
Only image blocks that are immediately to the left, right, above or below the empty space can be moved. The open
space should end up in the lower right hand corner when the puzzle has been solved.
You choose a puzzle configuration (rows and columns) from the dropdown at the top and you pick the image to use from a dropdown below the puzzle.
There is a reset button (pair of blue arrows) that can be used to reset the puzzle back to its original state. This also resets the number of moves to 0 and resets the timer so you can try again.
There is also a new puzzle button that changes the starting arrangement. The timer starts when you make your first move.