Lord Hanuman is known for his devotion to Lord Rama. He is the son of Anjana and Kesari and blessed by the God of wind, Vayu. Hanuman is celebrated for his devotion to Lord Rama. It is believed that Hanuman is an avatar of Lord Shiva or Rudra Avatar. Several texts present him as an incarnation of Lord Shiva.
Here is why Lord Hanuman is known as an incarnation of Lord Shiva OR Rudra Avatar
After Vishnu agreed to be born as a man to defeat Ravana, Brahma felt that he would need help, so he asked Shiva to take on an avatar as well. Shiva decided to born as Hanuman, the son of Vayu the wind god and the Apsara Anjana who had been cursed to the form of a monkey.
Like Rama who was unaware he was an avatar of Vishnu, Hanuman had no idea he was an avatar of Lord Shiva.
As a child, Hanuman was very mischievous. One time, soon after he was born, Hanuman attacked the sun thinking it was a piece of fruit, and when the sun ran away, he kept on chasing it! Despite being naughty as a young monkey, Hanuman was extremely loyal and courageous.
Hanuman’s best friend Sugriva was the brother of Vali, the king of Kishkindha, the land of the monkeys. Through a misunderstanding, Vali chased Sugriva out of Kishkindha and exiled him. Hanuman was the only one to accompany Sugriva in his exile. Hanuman showed just as much loyalty, if not more, to Rama as he did to Sugriva.
When Rama met Hanuman during his search for Sita, the two became instant friends. They were supposed to become instant friends as the event was pre-planned by supreme gods. Hanuman was the one responsible for locating Sita and telling her not to lose hope, that Rama was coming for her. During the battle between Rama and Ravana, Rama’s army was badly injured and many were killed. Upon seeing the devastation, Hanuman left to find a life-restoring herb called “Sanjeevani Booti” located on a far-off mountain, Dronagiri range of the Himalayas in Uttarakhand.
When he reached the herbs, he realized that there was no time to pick them, and in his devotion and loyalty, he lifted the entire mountain and carried it back to Rama and his men. Without Shiva as Hanuman, I doubt that Rama would have been able to save Sita in time. I still believe that Rama would have defeated Ravana, but without Hanuman by his side, the battle would have been much more difficult.
Hanuman as an avatar of Shiva is not accepted by everyone, but there are still many people who believe it. It makes sense to me that Brahma would want another one of the gods to assist Vishnu on his quest. As Ravana was a great devotee of Lord Shiva, it was nearly impossible to defeat him.
As we look into the story of Ramayana, if Hanuman had not been there, then Rama would have taken too long to find Sita and not made it back in time to keep Bharata from killing himself and the whole story would have been different.
Lord Hanuman was born on the full moon day (Purnima) of the month Chaitra on Tuesday. Tuesday is considered a very auspicious day to worship Lord Hanuman.