Three parallel horizontal lines drawn using ash on the forehead of Shiva devotees is known as the Tripundra. The Tripundra is made using bhasma or vibhuti and is a symbol of purification, rejuvenation and destruction. A red dot in the center of the Tripundra symbolizes Goddess Shakti.
The three parallel horizontal lines are also drawn on the sides of the arms by some Shiva devotees. Some Shaivites apply ash on the entire forehead.
Usually the three horizontal lines are made using ash but there are also many devotees who make Tripundra on forehead using sandalwood paste with a red dot in the center.
Another popular Tilak applied by Shiva devotees is the half-moon or Ardha-Chandra with a red dot in the center. The half-moon and the red dot represent Shiva and Shakti.
Another popular Tilak used by Shiva devotees is the trishul (trident) which is drawn on forehead using ash or sandalwood paste.
Staunch Shiva devotees who are no longer associated with society and lead the life of a mendicant apply ash on the entire body.
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