The circle is probably the simplest among the shapes. It has no vertices, no angles, and all the points on its circumference are equidistant to its center.
Hidden in the simplicity of a circle are its intriguing properties. The circumference of the circle when divided by its diameter is always equal to a single number () even if it is as small as an atom or as big as a planet. And what is more amazing is that the number is a neverending decimal where no portion repeats periodically.
The circle is the only shape that has infinitely many lines of symmetry (the equilateral triangle has only three and the square has only four). Draw a line passing through its center, and you are sure that the shape on one side is the exact copy of the shape on the other side.
There are also things that are better circular than not. A liquid in a square-rimmed cup will likely spill if you do not use the corner when drinking, and driving a car with a square wheel will surely be bumpy. Even things that we ignore, like manholes are better circular, so that their covers do not fall into its hole. On the other hand, there are also things that are forced to be circular even if they should not be (for the sake of beauty perhaps?) like the circular bookshelf shown below.
Circles in three dimensions are spheres and they are useful too. Without spheres, there would be no ball games — no basketball, no baseball, no billiards, etc., — so life would surely be a hundred times boring. There would be no soothsayers too, since no spherical crystal balls would be available.
Spheres are popular here, but they are even more popular in outer space. The planets, the stars, and the moons, and anything larger than an asteroid are spherical (not really perfect sphere but close to it) in shape. In fact, theoretically, gravity assures us, that if Earth and other planets live long enough, they will approach the shape of a perfect sphere, since gravity pulls towards a particular center, and anything high will be pulled down eventually.
The beauty and usefulness of circle shows us that most of the time, the simple things, the things that often ignore, are the most useful.
Image Credits: Craft Collective, Wikipedia, We Love Maths