Hanuman or Bajrang Bali is a staunch devotee of Lord Sri Rama, the incarnation of truth and virtue. He has been addressed by Sri Tulsidas as Ram Bhakta Shiromani, or the crest jewel of all the devotees of Sri Ram. He is addressed by various names like Pawan Putra, Anjaneya and Hanuman.
Therefore, Hanuman Jayanti is the pious day on which Sri Hanuman descended on earth in order to serve the purpose of his eternal master, Lord Ram. and he, being an pure devotee of Sri Ram is revered by all Ram bhaktas.
Lord Hanuman is an ardent devotee of Lord Sri Rama and is widely known for his unflinching devotion to Sri Rama. Hanuman is the symbol of strength and energy. He is said to be able to assume any form at will, wield the gada (including many celestial weapons), move mountains, dart through the air, seize the clouds and equally rival Garuda in swiftness of flight.
Lord Hanuman is worshiped as a deity with the ability to attain victory against evil and provide protection. The puja for Hanuman Jayanti can be done in Brahma Muhurtam i.e. 4:43 am to 6:19 am on March 31 and from sunrise till 6:06 pm.