A sketch (familiarly, a crobard ) is a quickly made Dessin, by a show of hands, without search for details and in theory according to nature. He meets several aims: exercise for the draftsman, allowing him to refine and maintain the relationship between its visual perception, its spirit of synthesis and its manual motricity; documentary catch of sight, in order to use graphic elements later on; visual explanation, as communications tools. Lastly, a sketch can be a drawing preliminary to a more important work and more detailed, but in this case one will speak rather about Esquisse.

The sketch is a graphic tool of communication, it represents an instantaneous subjective perception of the author.

The sketch is also a cartographic tool .

It is used in Topographie to materialize the first outline of a site, a ground or a building.