The pentagram is a five-pointed star drawn with five straight lines, each line crossing two others, producing a central pentagon and five outer triangular points. It can be drawn in a single continuous movement without lifting the pen — a property that gave it special significance in magical traditions as a symbol of wholeness and containment. The word derives from the Greek pentagrammon — "five-lined" — and should technically refer to the five-pointed star rather than the pentagon (which is the pentagram's five-sided inner form).
The symbol's orientation carries meaning in many traditions: point upward (one point at the top, two at the base) represents the human being — the head above the four limbs, spirit above matter, the single ascending principle governing the four material elements. Point downward (two points at the top, one at the base) has been variously interpreted as the descent of spirit into matter, as the Venus symbol (the evening star sinking below the horizon) and — in the 19th century occult tradition — as the Baphomet or "goat's head" symbol of inverted values. The inversion is a relatively modern association; historically both orientations were used interchangeably.
What makes the pentagram geometrically extraordinary is its encoding of the golden ratio φ (1.618...) in every measurable proportion. The ratio of a diagonal to a side of the inner pentagon is φ. The ratio of the whole line to the shorter segment it cuts is φ. The ratio of the star's radius to the pentagon's radius is φ. The pentagram is, in this sense, the simplest possible geometric demonstration that the golden ratio is a structural property of five-fold symmetry — not an imposed proportion but an emergent consequence of dividing a circle into five equal parts.