Slitherlink Description

Slitherlink is a puzzle originally from nikoli; you can see their description of the puzzle here. The object is to draw horizontal and vertical segments of unit length that connect the dots so that a single closed loop is formed. The loop cannot intersect itself. Numbers in the grid indicate how many of the four potential segments surrounding that square are contained in the loop. The solution is unique.

Below is an example puzzle and its only solution.