Parallel lines have the same slope and never intersect. Two lines are parallel if their slopes are equal. The equation of a line parallel to a given line can be found using the point-slope formula with the same slope. Perpendicular lines intersect at a right angle. Two lines are perpendicular if the product of their slopes is -1. The equation of a line perpendicular to a given line can be found using the point-slope formula with the slope of the perpendicular line being the negative reciprocal of the given line's slope. Examples are provided of finding if lines are parallel or perpendicular and constructing parallel and perpendicular lines through a given point.