Symmetry is a property of figures that makes them look the same on both sides. For example, the letter T has reflection symmetry: when you view it in a mirror, its two sides appear to be identical. Symmetry can also be seen in patterns and drawings.
If you fold a shape or pattern along its line of reflection symmetry, the two halves will match up perfectly. A figure must have at least one line of reflection symmetry for it to be considered symmetrical.
A rectangle, for example, has four lines of reflection symmetry because it can be folded along all four symmetry lines and the halves will match up perfectly. You can also see the symmetry of shapes and objects in nature, such as mountains reflecting off of rivers or lakes.
Symmetry can also be seen in 3D objects, like boxes and containers that you find at your grocery store. A box may have two equal sides because it has a plane of symmetry that divides it into two identical halves.
Another type of symmetry is rotational symmetry, which means that a figure can be rotated about a central axis and still look exactly the same. The star and the colorful blob at the top of this article have rotational symmetry. The letters N, Z, and S have rotational symmetry as well. Rotational symmetry is different from reflection symmetry because the direction of the rotation is preserved.