In North America, the common name for the remains of a cigarette after smoking is a cigarette butt. The butt is typically about 30% of the cigarette's original length. It consists of a tissue tube that holds a filter and some remaining tobacco mixed with ash. They are the most numerically frequent litter in the world. Cigarette butts accumulate outside buildings, on parking lots, and on streets, where they can be transported through storm drains to streams, rivers, and beaches.

Source: Wikipedia