Polka Dot is a pattern consisting of an array of filled, large in size, in simple words Circles. As seen in picture I m wearing a polka dot crop top, it differentiates itself from the spot pattern, as polka dots are perfectly even and sized, while spots are irregular in spacing and shape. Now when you see a plain surface with perfectly shaped circles or dots on them, this pattern is called Polka Dot.
The pattern rarely appears in formal contexts, however, and is generally confined to more playful attire such as bathing suits and lingerie. Occasionally, white-on-black small dots appear on more formal clothing.
Polka dots became common on clothing in the late nineteenth century in the United Kingdom.