"The theory or practice in art of applying small strokes or dots of color to a surface so that from a distance they blend together" -- Merriam-Webster
Pointillism (also called Divisionism) is a form of symbolic art. The size of the applied dots is uniform, and chosen carefully to correspond with the overall size of the painting. Also, the colors that are used are chosen carefully to blend in properly. The style is classified as Post-Impressionism, or Neo-Impressionism, and it is the product of the Société des Artistes Indépendants (1884).
The term Pointillism originates from descriptions of paintings by Seurat. Important artists painting in this style were: