The Parallel Postulate is a fundamental principle in Euclidean geometry, formulated by the ancient Greek mathematician Euclid. It states that if a line intersects two other lines and the sum of the interior angles on one side is less than two right angles, then the two lines will eventually meet on that side when extended. This postulate is crucial for understanding the nature of parallel lines. It implies that through a point not on a given line, there is exactly one line that can be drawn parallel to the given line, a concept that distinguishes Euclidean geometry from non-Euclidean geometries, such as hyperbolic and elliptic geometries.