Shorts have to be 60 seconds or less. Shorts can get a TON of views in a real short time and reach audiences that would other wise never know you exist. With Youtube "shorts" a viewer can scroll through and it never stops showing the shorts. Shorts, in general, are more or less an advertisement of what one may have on their channel, or a rolling bill board. Of course, some run their channel off of just shorts. All individual based.