Sketches derived from Greek σχέδιος - schedios, "done extempore" are works of drawings that are not usually meant to be the work of the end. A sketch can have several goals: recording something the artist sees, recording or developing ideas for later use, or can be used as a quick way to describe images, ideas, or principles.
When I get bored, I usually make sketches to entertain myself and pour inspiration with artwork and put it on the wall of the room