Guru Har Krishan Sahib Ji (Punjabi: ਗੁਰੂ ਹਰਿ ਕ੍ਰਿਸ਼ਨ [ɡʊru həɾ kɾɪʃən]; 23 July 1656 – 30 March 1664) is the eighth of the eleven Sikh Gurus. He became Guru Ji on 7 October 1661, succeeding His Father, Guru Har Rai. After His death from smallpox, His Granduncle, Guru Tegh Bahadur, became the next Guru Ji of the Sikhs.

Guru Har Krishan Sahib Ji was born in Kiratpur Sahib, Rupnagar, Punjab, India to Guru Har Rai and Kishan Kaur (Mata Sulakhni Ji). Before His death in October 1661, Guru Har Rai designated his younger son Har Krishan as the next Guru. Har Rai chose Har Krishan, rather than his elder son Ram Rai, because Ram Rai was in collusion with the Mughal Empire. Har Krishan was only five years old when he succeeded his father as Guru.

When Guru Har Rai Ji was asked who among his two sons Ram Rai and Har Krishan would be the next guru. Guru Ji asked the person to go with a needle and insert the needle in the leg of the bed where these two sat and recited baani. The sevadaar did the same and he was surprised to see that the needle went inside the bed when Guru Har Krishan Ji was doing paath but not when Baba Raam Rai was doing it. The sevadaar obviously perplexed went to Guru Har Rai Ji to ask the meaning. Guru Ji explained that although both of them were reciting the same baani, needle going inside the bed was symbolic of softness in the heart of Har Krishan Ji and baba Ram Rai was rough in the heart. Since the child guru was to take up so many diseases on his own self, softness was of prime importance. Thus next Guru came to be Guru Har Krishan Ji at the age of 5 years. Its the first time in the history when the light of the Guru had entered a small child.

Guru Har Rai (Punjabi: ਸ੍ਰੀ ਗੁਰੂ ਹਰਿ ਰਾਇ ਜੀ [ɡʊru həɾ ɾɑɪ]; 26 February 1630 – 6 October 1661) was the seventh of ten living Gurus of the Sikhs who became Guru on 8 March 1644 following in the footsteps of his grandfather, Guru Har Rai, nominated five year old Har Krishan, his youngest son as the next Guru of the Sikhs. The following is a summary of the main highlights of Guru Har Rai's life:

Just before his death at age 31, Guru Har Rai passed the Gaddi of Nanak on to his younger son, the five year old—Guru Har Krishan.

Guru Har Rai was the son of Baba Gurdita and Mata Nihal Kaur (also known as Mata Ananti Ji). Baba Gurdita was son of the sixth Guru, Guru Hargobind. Guru Har Rai married Mata Kishan Kaur (sometimes also referred to as Sulakhni) the daughter of Sri Daya Ram of Anoopshahr (Bulandshahr) in Uttar Pradesh on Har Sudi 3, Samvat 1697. Guru Har Rai had one daughter and two sons: Baba Ram Rai and Sri Har Krishan.

Although, Guru Har Rai was a man of peace, he never disbanded the armed Sikh Warriors (Saint Soldiers), who earlier were maintained by his grandfather, Guru Hargobind. He always boosted the military spirit of the Sikhs, but he never indulged in any direct political or armed controversy with the Mughal Empire. Once, Dara Shikoh (the eldest son of emperor Shah Jahan), came to Guru Har Rai asking for help in the war of succession launched by his half-brother the murderous Aurangzeb. The Guru had promised his grandfather to use the Sikh Cavalry only in defense. He, nevertheless, helped him to escape safely from the bloody hands of Aurangzeb's armed forces by having his Sikh warriors hide all the ferry boats at the river crossing after they had been used by Dara Shikoh in his escape.

Harjinder Singh Dilgeer (or Harajindara Siṅgha Dilagīra) is a writer on Sikh culture and history. Dilgeer wrote about the concept and the history of Akal Takht Sahib, Sikh culture, Shiromani Akali Dal, the history of Anandpur Sahib, and Kiratpur Sahib. The Sikh Reference Book is his magnum opus. He has produced a Sikh Encyclopaedia CD-ROM. His latest works are Encyclopaedia of Jalandhar (English), Dictionary of Sikh Philosophy (English and Punjabi), Banda Singh Bahadur (Punjabi), Makhan Shah Lubana (Punjabi), Sikh Twareekh in five volumes (a complete Sikh history, from 1469 to 2007, in Punjbi), and an English translation of Nitnaym (the Sikh daily prayer).^{[citation needed]}

Dilgeer was born in the family of Gurbakhsh Singh and Mata Jagtar Kaur, at Jalandhar, Punjab, India. in a family originally from Jaisalmer, in Rajasthan, then Mehraj village (now in Bathinda district). He was later based in Jalandhar and Jalalabad (Firozpur), and finally in Oslo. He is a citizen of Norway, and, presently lives in England.

Harjinder Singh Jinda was a member of a Sikh organization Khalistan Commando Force and one of the two assassins of Arun Vaidya (the Chief of Indian army at the time of Operation Bluestar and architect of Operation Bluestar). He was responsible for three high-profile killings; Arjan Dass, Lalit Maken and Gen. Vaidya. He along with other members of Khalistan Commando Force participated in Indian history's biggest bank robbery of Rs. 5.70 crore ($4.5 million) from Punjab National Bank, Miller Gunj branch, Ludhiana to finance the campaign for a separate Sikh state of Khalistan.

Harjinder Singh's mother's and father's names are Gurnam Kaur and Gulzar Singh. Jinda had two older brothers, Nirbhail Singh and Bhupinder Singh and one sister, Balvinder Kaur. Harinder Singh alias Mathra Singh and Jagjit Singh were nephews of Harjinder Singh Jinda. Sikh militant Surjit Singh Penta (who committed suicide by consuming cyanide during Operation Black Thunder in the year of 1998) was a cousin of Harjinder Singh Jinda. He belonged to a farmer family.

Guru-da-Gaddi is an important occasion of Sikh Religion. This is the time when the tenth Guru of the Sikh Religion had stated that the next Guru would be the Holy Sikh Book Guru Granth Sahib.

The Sikh religion has ten gurus. The tenth Guru, Guru Gobind Singh, declared that Guru Granth Sahib would from that moment on be the Guru or the Guiding Force. The message was delivered on 3 November 1708 by Guru Gobind Singh Ji at Nanded in the state of Maharashtra in India.

Guru Gobind Singh Ji established Khalsa and conferred the status of the Guru to the Guru Granth Sahib and elevated it as the everlasting Guru.

This event is commemorated with a festival/ritual that starts with Diwali in India - a Hindusikh festival. The tercentenary celebrations of the occasion are being referred at Guru-da-gaddi and are being celebrated on 3 November 2008 in Nanded in Maharshtra. The occasion comes after celebrations of 300 Years of Khalsa panth established by Guru Gobind Singh ji in 1699.