Wikipedia defines a poncho as:
In its simplest form the poncho is essentially a single large sheet of fabric with an opening in the center, for the head, and often it has an extra piece of fabric serving as a hood.
Alternative ponchos are now designed as fashion items. They are the same shape but of different material. These ponchos are designed to look fashionable and provide warmth while remaining breathable and comfortable, rather than to ward off wind and rain. These are often made out of wool or yarn, knitted or crocheted. Ponchos with festive designs or colors can be worn at special events as well.