Army Day is celebrated on 15 January every year in India, in recognition of Lieutenant General K. M. Cariappa's taking over as the first Commander-in-Chief of the Indian Army from General Sir Francis Butcher, the last British Commander-in-Chief of India, on 15 January 1949. The day is celebrated in the form of parades and other military shows in the national capital New Delhi as well as in all headquarters. On 15 January 2017 India celebrated its 69th Indian Army day in New Delhi. Army Day marks a day to salute the valiant soldiers who sacrificed their lives to protect the country and the people living in it.

Answer: Around 450 BC.

King Numa Pompilius is said to have added the months of January and February to the Roman calendar.

National Girl Child Day, also known as Balika Divas, is celebrated on January 24th every year to raise awareness about the importance of girls' education and their rights.

In 2006 the Council of Europe launched a Data Protection Day to be celebrated each year on 28 January, the date on which the Council of Europe's data protection convention, known as "Convention 108", was opened to signature. Data Protection Day is now celebrated globally and is called Privacy Day outside Europe.

On this date, governments, parliaments, national data protection bodies and other actors carry out activities to raise awareness about the rights to personal data protection and privacy. These may include campaigns targeting the general public, educational projects for teachers and students, open doors at data protection agencies and conferences.

The data protection convention, which is the only international treaty in this field, is being updated to ensure that its data protection principles are still in line with today's needs.

Pravasi Bharatiya Divas (English: Non-Resident Indian Day), is celebrated in India on 9 January every year to mark the contribution of the overseas Indian community to the development of India. The day commemorates the return of Mahatma Gandhi from South Africa in Bombay on 9 January 1915. Established in 2003, it is sponsored by the Ministry of External Affairs of the government of India and the Federation of Indian Chambers of Commerce and Industry (FICCI) the Confederation of Indian Industry (CII) and the Ministry of Development of the North Eastern Region of India. A celebratory event is held on 7-9 January every other year in an Indian city: a forum for issues concerning the Indian Diaspora is organized and the Pravasi Bharatiya Samman Awards are given.

Many European countries began making January 1 the official start of the New Year in the 16th century.

January 1 was sometimes called Circumcision Style because it was the date of the Feast of the Circumcision.

30th January is celebrated as Martyrs’ Day and World Leprosy Eradication Day.

World Braille Day is celebrated on January 4th every year to raise awareness about Braille, which is a form of written language for blind people.

Republic Day honours the date on which the Constitution of India came into effect on 26 January 1950 replacing the Government of India Act (1935) as the governing document of India.

The Constitution was adopted by the Indian Constituent Assembly on 26 November 1949, and came into effect on 26 January 1950 with a democratic government system, completing the country's transition towards becoming an independent republic. 26 January was chosen as the Republic day because it was on this day in 1930 when Declaration of Indian Independence (Purna Swaraj) was proclaimed by the Indian National Congress as opposed to the Dominion status offered by British Regime.

It is one of three national holidays in India, the other two being Independence Day and Gandhi Jayanti.

Annually held on January 26, International Customs Day (ICD) recognizes the role of customs officials and agencies in maintaining border security. It focuses on the working conditions and challenges that customs officers face in their jobs.