Street art is a form of contemporary art created in public spaces rather than traditional galleries or museums. It includes various styles such as graffiti, stencil painting, posters,urban collages and 3d street art. One particularly fascinating branch of street art is optical illusion design, which has gained a large following. This style relies on perspective techniques and is often made with chalk on sidewalks or walls, creating a three-dimensional effect. Some of the well-known artists in this field include Kurt Wenner from the United States, Julian Beever from the United Kingdom, Leon Keer from the Netherlands, and Saleh Sokhandan from Iran.