Govardhana Puja is celebrated during the month of Karttika. This festival embodies Krishna’s eternal pastime where He lifted the Govardhana Hill to protect the residents of Vrindavan.
Lord Krishna, the Supreme Personality of Godhead, saw the residents of Vrindavan preparing things for the Indra-yajna (Indra worship), He suggested them to stop worshiping the demigod Indra (the demigod of rain) and instead serve Govardhana hill. When Indra came to know about this, he became very angry and sent heavy rains and storms to Vrindavana. At this, Krishna lifted the entire Govardhana hill with the little finger of his left hand and gave refuge to the residents of Vrindavan.
Indra then realized his own mistake and apologized to Krishna. Thus the Supreme Personality of Godhead Sri Krishna taught that His devotees are not bound to worship demigods.