In Human Design, a Line refers to one of the 6 positions within a hexagram. Each of the 64 Gates has 6 lines (numbered 1 through 6), and each line represents a specific expression, role, or stage of that Gate's overarching theme. The lines are divided into the Lower Trigram (lines 1, 2, 3 — personal/inward focus) and the Upper Trigram (lines 4, 5, 6 — transpersonal/outward focus). The 6 lines correspond directly to the 6 Profile Lines: Line 1 (Investigator — builds foundational security through knowledge), Line 2 (Hermit — natural genius waiting to be called), Line 3 (Martyr — learns through trial and error), Line 4 (Opportunist — life operates through relationships and network), Line 5 (Heretic — the practical revolutionary, universalizer), Line 6 (Role Model — the sage living through three phases: fall, on the roof, and model). Every planetary activation in a BodyGraph has a specific line designation that contributes to the individual's Profile.