Republic Day marks the adoption of India's constitution and India's transition from a British colony to a republic on January 26, 1950.
As per the Government of India's website (mygov.in), every year, the celebrations marking the day feature spectacular military and cultural pageantry.

In the year 1950, on January 26, the Constituent Assembly officially adopted the new constitution, making India a republic. The day is now celebrated as Republic Day in India. The Indian National Congress declared the end of colonial rule on this day in 1930.