Parallel lines go in the same direction but do not intersect. E.g. two sides of a piece of paper.
Perpendicular lines are lines that intersect at a right angle. E.g. two lines crossing to form an ‘x’, if any one of the angles are 90° then all four of the angles will be 90°. If the lines intersect but none of the angles are at 90° then they are neither parallel not perpendicular.
Lines of symmetry perfectly divide a shape into multiple identical parts. E.g. dividing a square into four equally sized quadrants.
Right angles are formed when a horizontal line is met by a perfect vertical line at 90°.
Acute angles are any angles smaller than a right angle and therefore less than 90°.
Obtuse angles are any angles larger than a right angle and above 90°.