Logic puzzles are puzzles where you are given a certain set of rules, and must deduce the solution from those rules using logic.
Examples:
Dominosa is a puzzle where you have an arrangement of dominoes with only the numbers kept, edges being removed, and you must find the original arrangement of dominoes.
In Slitherlink, you have a grid with numbers in each square, and dots as the corner of each square. Your goal is to place edges, each connecting two dots, to create a looping path. No loose ends, no branching or self-intersecting paths. The numbers represent how many edges of the square are filled in.