On Monday 26th January 2015, India celebrates 66th Republic Day.
Independence Day (15th August 1947) was when India got its freedom from the British ruling.
Then, the Constitution was launched on 26th January 1950. This is the day called Republic Day.
The Constitution is a set of rules to run a country.
On a Republic Day, Indians hoist the Indian national flags in different parts of India, and they also do Parades, where the soldiers, school children and decorated trucks move on long routes and people watch.
On this day, the Indian Prime Minister Narendra Modi and the President Pranab Mukerji will attend the parade and give a speech.
For the first time the American President Barack Obama is attending the parade on the Republic Day.