2D Shapes & Symmetry

We name many 2D shapes by their number of straight sides:

A line of symmetry is a fold line that splits a shape into two halves that match exactly — fold along it and the two halves land right on top of each other.

Worked example. Which shape has $4$ equal sides and $4$ square (right-angle) corners?

Four equal sides and four right angles describe a square. A rectangle also has four right angles, but its sides are not all equal.