Drums are percussive instruments built by stretching a membrane across an opening in a vessel. The most common property of various types of drums is their pitch. Drums are the one of the oldest and the most omnipresent instruments. Even with the various types of drums present, the most common aspect is the origin of sound. Sound in a drum originates from the vibration caused when you strike the membrane, called the head, with another object. Drumheads can be made from the skin of a goat, cow, antelope, or sheep, or even a synthetic material. The types of drums that exist vary as markedly as the people who use them for communication, ritual, or entertainment all over the world. The common way of classifying drums into different types of drums is by their shape. Most drums fall into the Zakk Wylde guitars following categories cylindrical, barrel, conga, waisted, goblet, or bowl. A frame drum, with its squat hoop, and a long drum, which is thin and tall, are both the cylindrical variety. A barrel such as a Tabla, goblet such as a Djembe, and bowl such as a Nakari, are named for their shapes so they are easily recognized. The conga tapers at its bottom, and the waisted drum tapers in the middle, as with a Changko’s cinched waist. A further classification on the types of drum is made on the basis of which side the drum might have a head. A drum may have a head at either end of the body or only on one. Drums like congas and bowls have one head, but frame drums have two. Some drums can be carried while walking or dancing while some drums are stationary, such as the Djembe from Mali.