The violin is played with a bow or with the fingers. The bow consists of the stick, the frog, the tip and the hair. The bow stick must be very flexible and is usually made of pernambuco wood/brazilwood.
Even a violin bow made by a master can cost up to several hundred thousand euros.
The bow hairs are attached between the tip and the frog. The frog is the part of the bow where you adjust the tension of the bow hairs. It is also where the bow is held.
The bow hairs are usually made of horsehair. As the horsehair is too smooth to make the string vibrate, it is rubbed with rosin. This tree resin increases the friction of the hairs so that a nice even tone can sound.