There is no foolproof logical way to solve this seemingly easy puzzle. Or, as Nikoli puts it, 'the puzzle requires inspired guessing and puzzling sense.'
A typical puzzle consists of an 8x8 grid. The numbers 1-8 appear twice in the grid. All numbers appear to be placed randomly. The objective is to link each pair of numbers with a line without crossing a line drawn between any other pair of numbers.
One key to solving is to consider number pairs near the border that can be connected without cutting off any of the other numbers.