A puzzle from 2-dimensional or 3-dimensional geometry centered around matchsticks, often involving moving, adding, or removing some to achieve some defined goal.

Question is about the connecting and joining of 2D or 3D lines of unit-length. A commonly used object for visualizing are matchsticks, but could as well be pencils, pens, sticks, or even needles. The matchsticks may be moved around or removed, or some may be added, to achieve some goal.

Some kinds of puzzles using this tag: