Every year 23 March is celebrated as Shaheed Diwas or 'Martyrs' Day'. On this occasion, the martyrs who sacrificed their lives for Indian independence are honored and their sacrifices are remembered.

History of Shaheed Diwas:

On March 23, 1931, the British hanged India's young freedom fighters Bhagat Singh, Shivram Rajguru and Sukhdev Thapar. This day is celebrated to pay tribute to the immortal martyrs who sacrificed their lives smilingly in the freedom struggle.
The names of Shaheed Bhagat Singh, Sukhdev and Rajguru are recorded in golden letters in history. Shaheed Bhagat Singh, Sukhdev and Rajguru are role models and inspirations for the youth. All three were sentenced to death on charges of Lahore conspiracy.
March 24, 1931 was fixed as the date of hanging of Bhagat Singh, Sukhdev and Rajguru. But the British government hanged him on March 23, a day before the scheduled time. Because the British government was afraid that the countrymen would get angry by hanging these revolutionaries.
In this situation, the three brave sons were secretly hanged a night before the scheduled date.

Shaheed Diwas is celebrated on a total of eight dates in India:

In honor of the Shaheed, not only March 23 but a total of eight Martyrs' Days are celebrated in India every year. These eight days are 30 January, 23 March, 19 May, 13 July, 21 October, 17 November, 19 November and 24 November. Their chronological order is being mentioned as follows:

On January 30, 1948, Nathuram Godse assassinated Mahatma Gandhi by shooting him.
Bhagat Singh, Sukhdev and Rajguru were hanged by the British on 23 March 1931.
On May 19, 1961, the government mercilessly opened fire on people protesting for their mother tongue at Silchar station in Assam. Martyrs' Day is celebrated on 19 May in memory of 15 people killed by the state police.
On 13 July 1931, 22 people were killed by royal troops while protesting against the rule of Maharaja Hari Singh of Kashmir. To remember these 22 people, Jammu and Kashmir observes July 13 as Kashmir Martyrs' Day.
On October 21, 1959, he was ambushed by an armed Chinese contingent in the Hot Spring area of Ladakh. 10 brave police personnel sacrificed their lives in this attack. October 21 is observed as Police Memorial Day to honor the memory of martyrs and all other policemen who have lost their lives in the line of duty.
On November 17, 1928, Lala Lajpat Rai, a freedom fighter and Punjabi writer, was martyred.
Rani Lakshmibai's birth anniversary, 19 November, is celebrated as Jhansi Martyrs' Day. Lakshmibai was martyred on November 19, 1857.
24 November is celebrated as Martyr's Day by the Sikh community. Because it is the death anniversary of the ninth Sikh Guru Tegh Bahadur. Guru Tegh Bahadur had opposed the forced conversion of non-Muslims. He was publicly hanged by the Mughal emperor Aurangzeb on 24 November 1675.