Vamana Avatara is regarded as the fifth incarnation of Lord Vishnu. Lord Vamana is also known with epithets Vikrama, Trivikrama, Urukrama, Upendra, Dadhivamana, Balibandhana, Aditya, Kaashyapa, Aditinandana and Vamanadeva. An account about Lord Vamana is also found in Rigveda.

Descriptions of Lord Vishnu's Vamana Avatara are found in various religious texts including Bhagavata Purana, Vishnu Purana and Vamana Purana. Lord Vamana was born to Sage Kashyapa and His wife Aditi. Among the Dwadasa Aditya, Lord Vamana is revered as the twelfth Aditya. Lord Vamana is the younger brother of Lord Indra.
According to the description found in Srimad Bhagavatam, once, King Bali defeated Indra in a battle and established His reign on Deva Loka. The father of King Bali was Virochana, who was the grandson of Bhakta Prahlada, the great devotee of Lord Vishnu. King Bali was respected as a compassionate demon and king. According to beliefs, King Bali established his reign on three worlds with the power of his Tapas and valor, and as a consequence, he became exceedingly proud of his might.
Once, King Bali organised an Ashvamedha Yajna to declare his absolute sovereignty on Earth as the king of all kings. Upon learning about the event of Ashvamedha Yajna, Indra and other Gods became worried and appeared before Mother Aditi and narrated the cause of their misery to her. When Mother Aditi saw her sons in such an agitated state, she performed intense penance to propitiate Lord Vishnu. Pleased with her penance, Lord Vishnu appeared before her. Mother Aditi expressed her wish that Lord Vishnu take birth as her son. Granting her wish with the exclamation Tathastu, Lord Vishnu vanished from the sight. In due course, Lord Vishnu was incarnated as Lord Vamana from the womb of Goddess Aditi.
Beholding the Batuka Vamana Avatara of Lord Vishnu, joyous waves of happiness permeated in Gods, sages and all living beings, and they began hailing the Lord's name with profound devotion. Lord Vamana, in the form of a dwarf Brahmin youth, was carrying a Kamandalu, a Japa Mala and a wooden umbrella in His hands.
Lord Vamana, in the form of a Brahmin youth, appeared in front of King Bali. King Bali was renowned in all three worlds for his munificence. He would not let any supplicant return empty-handed from his palace. Upon seeing the Brahmin youth, King Bali greeted Him with folded hands and inquired about the purpose of His visit.
Lord Vamana requested King Bali to donate Him three strides of land. Upon hearing the request of only three strides of land, King Bali entreated Vamana Deva to ask for other supplications also. However, Shukracharya, the Guru of demons, realized the device of Lord Vamana and urged Lord Bali to not take an oath to make any donation. But King Bali refused to listen to the request of Shukracharya. Finally, to stop King Bali from making the oath, Shukracharya assumed a subtle form and installed himself in the spout of the Gangasagar vessel, thus obstructing the flow of water from the vessel.
Lord Vamana was omniscient and responded to Shukracharya's scheme in His own playful ways. He slid a blade of grass through the spout of the Gangasagar vessel, which gravely damaged one eye of Shukracharya. From that moment, the demon Guru Shukracharya possessed only one eye. Afterwards, Shukracharya still made various attempts to stop King Bali from making oath, but he could not deter King Bali from making the solemn vow of donating three strides of land to Lord Vamana. As soon as the vow was made, Lord Vamana expanded His form to an unimaginable magnitude and within a moment, the Lord transformed into a divine colossal being from a dwarf Brahmin.
Lord Vishnu, in His Virat form, covered the entire Earth in His first stride and Deva Loka in the second stride. As soon as Lord's divine foot touched the Deva Loka, Lord Brahma washed it with the water of His Kamandalu. After the ablution, the water that flowed down from the divine foot of Lord Vamana became the origin of Goddess Ganga. However, there was no place left to measure after Lord Vamana covered the entire Universe in just two strides. Then, Lord Vamana asked King Bali to fulfill his oath.
King Bali was renowned for his munificence and for his resolute commitment to his oath. Realizing that there was no alternative, he requested that Lord Vamana place His third step upon his head. Lord Vamana was extremely pleased with Bali's commitment and generosity. Because the great-grandfather of Bali was Prahlada, who was a great devotee of Lord Vishnu and is known in all three worlds as Bhakta Prahlada. Thus, Lord Vamana placed His third step upon Bali's head and fulfilled his vow of covering the entire creation in three strides.
According to the legend, as soon as Lord Vamana placed His third step upon Bali's head, King Bali descended to Patala Loka or Sutala Loka, the nether realm of the cosmos.
According to another legend, Lord Vamana, while placing His third step upon Bali's head, blessed him with immortality and gave him Darshan in His Virat or colossal form. Lord Vishnu, pleased with Bali's righteousness, conferred upon him the title of Mahabali. Afterwards, Lord Vishnu established Mahabali in Antariksha Loka, a divine realm above sky, where he met with Prahlada and other divine beings.
The father of Lord Vamana is Sage Kashyapa and His mother is Goddess Aditi. According to the description found in religious texts, Vivasvana, Indra, Varuna, Pusha, Aryama, Bhaga, Dhata, Parjanya, Anshuman, Tvashta and Mitra are His elder brothers. Collectively they are called twelve Adityas. Lord Vamana is celibate; thus He has no wife.
Lord Vamana is depicted as a dwarf Batuka Brahmin. He carries Chatra, a wooden umbrella and Lakuti, a stick in one hand and a Kamandalu in the other. In His Trivikrama form, He is portrayed with four arms while covering the entire creation with His three strides. In this form, He carries a conch, a discus, a mace and a lotus flower in each of His hands.
In Trivikrama form, He is portrayed covering Bhuloka with His first step and Swarga Loka with His second step while placing His third step on King Bali's head. In this form, Lord Brahma is shown washing the feet of Lord Vamana.
General Mantra -
ॐ वामनाय नमः।
Om Vamanaya Namah।
ॐ नमो भगवते दधिवामनाय।
Om Namo Bhagavate Dadhivamanaya।
Pranam Mantra -
देवेश्वराय देवश्य, देवसम्भूतिकारिणे।
प्रभावे सर्वदेवानां वामनाय नमो नमः॥
Deveshvaraya Devashya Devasambhutikarine।
Prabhave Sarvadevanam Vamanaya Namo Namah॥
Lord Vamana Gayatri Mantra -
ॐ तपरूपाय विद्महे सृष्टिकर्ताय धीमहि।
तन्नो वामनः प्रचोदयात्॥
Om Taparupaya Vidmahe Srishtikartaya Dhimahi।
Tanno Vamanah Prachodayat॥